Web-based social networks are a powerful communicative element and their use is increasingly widespread. Persons living in extreme social exclusion such as individuals experiencing homelessness can benefit from the positive elements of communication and relationship associated with social networking sites.This study aimed to suggest the comparison of a Facebook training course and an office software course and their effect on psychological well-being in a group of individuals experiencing homelessness.An experimental and longitudinal study was designed. Individuals experiencing homelessness were randomly assigned to either the Facebook group or the office software group, and their social skills, self-esteem, self-efficacy, and satisfaction with life were measured on 4 occasions: pretest, at the end of the training course, 1 month later, and 3 months later. A mixed analysis of variance of repeated measures (2×4) was performed.2=0.32); in the self-esteem and self-efficacy scores, it was medium, (η2=0.13); and in the satisfaction with life scores, it was small (η2=0.09). The results of the adjustment of the different models of multiple linear regression indicate that the number of hours devoted weekly to the use of Facebook was a predictor of the increase in the scores of social skills  and self-esteem (B=.382). Age (B=.175) and self-efficacy (B=.09) were also variables, which with independence and in equal conditions, predicted self-esteem (r2=.29). Finally, self-esteem (B=.69) was also a predictor variable of the increase of satisfaction with life (r2=.195).A total of 92 individuals experiencing homelessness participated in the study. The number of cases in which the 4 measurements were completed was 71 (35 in the intervention group and 36 in the control group). The mixed analysis of variance of repeated measures and the multiple regression analysis indicated a significant increase of the 4 analyzed parameters, with greater significance in the areas of social skills and self-esteem. The critical levels associated to the interaction Time×Program were significant in all variables and levels. Therefore, the scores in the 4 analyzed constructs were not equal according to the program carried out throughout the work. The effect size associated to the interaction Time×Program in the social skills scores was large (ηThese findings suggest that Facebook could be a key element in homeless psychological well-being and socialization. Homelessness is a situation of extreme social exclusion with very serious organic, psychological, and social consequences. Individuals experiencing homelessness display, when compared against the general population, higher levels and more acute episodes of mental health disorders  and assoWorks on loneliness in individuals experiencing homelessness have reported high levels of interpersonal isolation and self-alienation as a consequence of a situation of constant struggle for daily survival, violence, victimization, abuse, drug consumption, and social stigma ,9. All tWith the incorporation of SNS in daily life, scientific investigation of their influence on human behavior has proliferated, and behaviors related to homelessness are no exception. Until mid-2012, between 44% and 62% of individuals experiencing homelessness owned a mobile phone, between 24% and 40% owned a personal computer, and between 47% and 55% used the computer and accessed the internet .The use of SNS presents great opportunities to improve the health of individuals experiencing homelessness. Work carried out with homeless youths to prevent sexually transmitted diseases showed that there exists a high association between Web-based communication and a significant decrease in risk behavior related to HIV and hepatitis C exposure, as well as a higher perception of the risk of people exposed to the possibility of contagion of HIV and hepatitis C ,15. SNS Until now, studies carried out on the use of information and communication technologies (ICT) by homeless people recommended the development of formative proposals on learning how to use them. ICT use has been linked to an increase in levels of self-esteem and self-efficacy , which hThe aim of this study was to confirm whether a group of training sessions to capacitate individuals experiencing homelessness to use Facebook indicates an increase of their communicational uses and whether this improves the levels of social skills in the internet-based surrounding, self-esteem, self-efficacy, and satisfaction with life. It is expected that participants will achieve better marks in these psychological constructs and that this improvement will linger on in time.The study used a longitudinal prospective and experimental design, and a randomized controlled trial pretest-posttest with an intervention group and control group.A total of 92 individuals experiencing homelessness from a city in the northwest of Spain with approximately 100,000 inhabitants participated in the study. All participants were aged ≥18 years, and the recruitment took place from January to March 2017. The European Typology of Homelessness and Housing Exclusion (ETHOS) classification criterion was used to determine the condition of individuals experiencing homelessness . The ETHThe professionals in the harm reduction service in Girona who perform community tasks in outreach detected the cases of individuals experiencing homelessness. This team is part of the mental health and addictions public network that belongs to the Catalan government. Among others, one of its functions is to work with individuals experiencing homelessness on the street and to collaborate in shelters and at the city drop-in center, which is also public. The recruitment was carried out on the streets, in illegally occupied houses and the municipal shelter, bearing in mind the expertise that the team has in this kind of action.The criteria of inclusion were (1) being an adult; (2) not having a Facebook account or in the event of having one, claiming to have low knowledge of its use; (3) wishing to be trained in order to improve one’s skills; (4) partaking voluntarily in the study; (5) having good Spanish language skills; and (6) being included in one of the categories of homelessness according to the ETHOS classification of homeless people.The participants who met the criteria were assigned in a random, proportional, and stratified way, according to gender, origin (indigenous or foreign), and the weekly number of hours of use of SNS at intervention group or control group. The strata were defined bearing in mind that these are the principal variables that could bias the results of the study in the Spanish context . InitialFor the intervention group, an educational training course aimed at learning or improving the use of Facebook was designed: creation of an email account or recovering forgotten passwords; signing up on Facebook; designing a user profile; visualizing it (how we are presented on the net); privacy options; searching for people; requesting and accepting friends; sending pictures, videos, or private messages; creating and following groups.For the control group, a basic office software course similar to those offered by social services or nongovernmental organizations in the city to people with very serious risk of social exclusion was developed. For this purpose the contents of the 4 courses taught in different institutions in the area were gathered and homogenized: identifying the basic parts of a computer, switching it on and shutting it down, knowledge of the desktop and files, main uses of a text processer, saving documents, basic design of a curriculum vitae, access to the internet, exploring the main job search websites in Spain, creating email accounts, recovering passwords, and many more. Job search is a relevant component in office software courses offered to people at risk of residential exclusion, as work reinsertion is normally one of the main aims in the social services’ working plans.the distance between the actual developmental level as determined by independent problem solving and the level of potential development as determined through problem solving under adult guidance, or in collaboration with more capable peers [Both courses were carried out in sessions of 1.5 hours, once a week, for 8 weeks, in 2 rooms in 2 community sociocultural centers in the city. The training sessions were developed with prospective didactics, taking into account, as much as possible, the users’ previous experience, with individualized open attention. The training experience was based on the Zone of Proximal Development concept, that is, considering le peers . In otheIn order to facilitate this methodology, the participants were divided into small groups, and 12 university students collaborated in the project (6 for intervention group and 6 for control group), acting as trainers after they completed a 20-hour training session on office software, SNS, Facebook, and homelessness. In order not to condition trainers and to avoid bias in the study, they were not informed explicitly that it was an experimental intervention group or control group design. If necessary, the students introduced cross-study contents related to the social skills involved in the topics covered: for instance, the best way to address an employer  or examples of how to be assertive when commenting on a Facebook post.All participants were given an informative handout on the aims of the study and signed it. The students signed a confidentiality clause so as to preserve information regarding the participants.The pretest was carried out on the first day of training in both groups, and the first posttest on the last day, at the end. The posttests were carried out 1 month and 3 months, respectively, after the training ended. They were distributed in the shelter where the individuals experiencing homelessness received assistance, food, or sleep accommodations, or at the drop-in center where leisure and reinsertion activities were available. To assist those who were not found in these places, and to ensure maximum participation in the posttest, different professional teams of the net of attention to individuals experiencing homelessness sought the participants and reminded them systematically about the importance of the tests. In certain cases, the open medium team attended the places in which the individuals experiencing homelessness lived to ensure that the tests were completed. The investigators who administered the posttests did not participate directly in any of the training sessions in order to reduce the social desirability effect in the assessment of the participants. The investigation protocol was approved by the Ethical Committee on Biomedical Research of Girona (Cod. XSO_2017_23/05/2017).The participants’ sociodemographic information and self-reports of internet use were gathered through an adaptation of a questionnaire on the use of SNS in adult populations . At the The Multidimensional Scale of Social Expression-C  was usedSelf-Esteem Scale  is validThe General Self-Efficacy Scale  was adapThe Life Satisfaction Scale  was adapt test for independent and paired samples for quantitative variables. To determine the variability of measures in the scores of dependent variables social skills, self-esteem, self-efficacy, and satisfaction with life according to the type of program, a mixed analysis of variance of repeated measures (2×4) was applied for each. Observations were carried out pretest-posttest at the beginning of the training (T1), at the end of it (T2), 1 month later (T3), and 3 months later (T4). Subsequent post hoc contrasts (Bonferroni) were carried out, and the extent of the effect and potency were observed. On the other hand, the scores from each observation were correlated with the Pearson test, and a multiple linear regression model was adjusted for each of the variable dependents social skills, self-esteem, self-efficacy, and satisfaction with life including the quantitative variables age and number of hours using SNS in the model, with the aim of determining the predictor variables of increase in the analyzed psychological constructs.Central tendency and dispersion measures for the description of data were used. The sociodemographic variables for intervention group and control group were compared with the results of a chi-square test for the qualitative variables and the Student A total of 21 participants were discarded on the grounds of not completing the posttest measures. The number of cases in which the 4 observations were completed was 71 (35 in the intervention group and 36 in the control group). Among the participants, 79% (56/71) were men, with an age average of 39 (SD 8.86) years and 55% (39/71) were foreign (not born in Spain). In the pretest, 69% (49/71) of participants claimed to have an email account and 68% (48/71) claimed to use Facebook at any time. The people with a registered profile accessed Facebook an average of 1.2 (SD 1.3) hours a week with the principal intention of contacting family  or friends  or having free time and leisure . As can be observed in 2=0.32), whereas in the self-esteem and self-efficacy scores, it was medium, (η2=0.13), and in the satisfaction with life scores, it was small (η2=0.09), following the Lacobucci interpretation [The repeated-measures mixed analysis of variance indicate that the critical level associated with the Time factor was <.05 in the evolution of the 4 levels of analysis of social skills, self-esteem, and satisfaction with life, but not self-efficacy. Regarding the Program factor and the interaction Time×Program, the results were significant for all variables and levels. Therefore, the scores in the 4 analyzed constructs were not equal according to the program carried out throughout the work. In the social skills scores, the effect size associated with the interaction Time×Program was large . The post hoc analysis (Bonferroni) indicated that in the Time×Program interaction, albeit there were no significant differences between the scores of both groups when the pretest was carried out , differences did exist at the end of the intervention , 1 month later , and 3 months later . The difference in averages at each level may be observed in the graphic representation of the evolution of scores (The difference in averages in the Program factor (intervention group−control group) was 26.61 points , T2-T3, T2-T4, T1-T3, and T1-T4. The measure between levels T3-T4 displayed a tendency toward significance .The effect on the intragroup tests was significant in the measures T1-T2 was −27.91 points , between T2-T3 was −14.57 , between T1-T3 was −42.49 , and between T1-T4 was −40.89 . t test analysis for related samples carried out for each of the dependent variables. We can say that the program was effective at increasing social skills for the intervention group but not the control group, and this improvement lingered on in time until 3 months after the intervention.The analysis of averages for related tests for each group showed that in the intervention group, the average difference between TF1,69=7.47, P=.008). In the pretest, there were no differences in the interaction Time×Program in the scores of the 2 groups . In the observation T2 corresponding with the posttest, there were differences between the averages  and likewise in T3. In T4, despite a slight tendency toward significance, there were no observed differences .In the case of self-esteem, the difference between the averages in the Program factor (intervention group−control group) was 2.61 points , T2-T4, and T1-T3 and also T1-T4 and T3-T4. There was no significance in the level T2-T3.In the intragroup tests, there were significant differences in the observations corresponding to Tt test for paired samples analysis indicated an increase of average scores in the intervention group of −2.74 between T1-T3, it did not happen with T1-T4: mean −0.57 (SD 3.90), t34=−87, P=.39. Therefore, the effect of the intervention expired between 1 and 3 months after the intervention. On the other hand, a decrease in the average scores of self-esteem in the control group between T2-T3 , T1-T3 , and T1-T4  was observed . No differences were observed in time regarding the averages between groups T1. There were differences between T2, T3, and T4.Regarding self-efficacy, there was a difference in the averages in Program (intervention group−control group), of 9.03 points , T1-T3, and T1-T4, but not in the rest of the levels ; see In the intragroups test, there were significant differences between T1- T2 comparison . In the intervention group, the self-efficacy scores increased from the pretest to the observations 1 month later  and 3 months later . Contrarily, in the control group, they decreased in the measurement 1 month later .The independent measures made for each of the groups displayed significant average differences in both groups in the TF1,69=7.23, P=.009). In the post hoc tests, as can be observed in 1: F1,69=.42, P=.52) or in the last level . Contrarily, differences were found in T2 and in T3.Regarding satisfaction with life, the Program factor displayed a difference of averages (intervention group-control group) of 1.47 points , T1-T3, T2-T4, and T3-T4. Contrarily, no differences were found between T1-T4 and T2-T3.In the intragroup tests, there were significant differences between Tt test for paired samples in each group displayed differences in the averages in T1- T2, T1-T3, and T1-T4. No differences were found in the control group.The independent measurements carried out with the Student t34=−13.11, P<.001), and this number continued increasing at the end of the course, until 3 months later it reached ≥2 hours , with a total increase for T1-T4 of 10 hours a week . The control group, on the other hand, did not display an increase in hours of use from the pretest to the end of the training course , but it did 3 months later, with an average of 1 hour a week . The average number of hours of use 3 months after the end of the training course was significantly higher in the intervention group than in the control group . The variables corresponding to the weekly number of hours and age were also included in the linear regression model. The correlations corresponding to each of the quantitative variables in each level of observation (pretest and 3 posttests) were carried out with the r for the Pearson test. These data can be seen in The comparison of averages for paired samples carried out in the intervention group and control group to verify the variability in the weekly use of Facebook indicated that in both groups there was an increase in the number of hours. Between the pretest and the posttest at the end of the training course, participants in the intervention group increased their use of Facebook an average of 8 hours a week  and self-esteem (B=.382). Age (B=.175) and self-efficacy (B=.09) were also variables that, with independence and in equal conditions, predicted self-efficacy (r2=.29). Finally, self-esteem (B=.69) was a predictor variable of the increase of self-efficacy  claimed that their principal motivation for using SNS was to communicate with another person: 57% (19/33) with family and 30% (10/33) with friends. The rest used SNS for leisure or regular access to information .t69=−.33, P=.74), although there did exist differences in the usefulness perceived by participants . A total of 7 participants of the intervention group expressed their refusal to repeat the training course to learn concepts more in depth, compared with 15 participants of the control group .Finally, the general satisfaction with the course results did not show score differences between the groups .The results obtained indicate that improving the use of Facebook contributes to the improvement of the psychological constructs in individuals experiencing homelessness and that this improvement does not disappear until at least 1 month after the intervention . Therefore, the expected results are verified: participants in the program improved their scores in social skills, self-esteem, self-efficacy, and satisfaction with life, and this improvement continued over time. The improvement of the social skills in the internet context was accentuated in comparison to the rest of the analyzed variables. An analysis of the general population for any differences in social skills in the internet context and in “real” context revealed the existence of significant discrepancies in the results of both in inversely proportional relations . This faThis fact is very interesting in the analysis of the social relationships of individuals experiencing homelessness who preserve their secure and private space with mistrust. More prosocial and healthy relationships are generated in the SNS, as opposed to relationships in their closest surroundings, the street, or special centers devoted to offer social assistance . Thus, tLearning to use Facebook fulfills two objectives: to improve the process of resocialization, soothing the effect of the hard situations faced, and to increase self-esteem. The reasons for this are access to information that the individual can filter and on the other hand and more importantly to provide individuals experiencing homelessness a way to contact friends and relatives through SNS . Self-esOther known proposals in basic office software training courses among individuals experiencing homelessness that explored the experience of using computers with a group of individuals experiencing homelessness without experience in the use of ICT, produced great acceptation and good attitude toward ICT . After tThus, in basic office software training courses for people at risk of social exclusion, it is usually first assumed that unemployment is one of the main causes of homelessness, both in individuals experiencing homelessness and in the general population and second that the aim of the professionals who design the course is to reduce homelessness .Nevertheless, despite the fact that unemployment is one of the structural causes of homelessness and access to employment increases the possibilities of inclusion in the general population, there should be an assessment of the most adequate strategies for job searching through ICT, especially with individuals experiencing homelessness and their different typologies.Other studies support the finding that interventions based on specific occupational therapy for individuals experiencing homelessness are effective, given the distinctive therapeutic features of this type of intervention, which is not merely a training course . In factRegarding satisfaction with life, it is noteworthy to point out that the perception that individuals experiencing homelessness have of satisfaction with life is significantly lower than that of the general population . These rThis complex situation is coherent with the results of this study. The levels of satisfaction with life can rise at the beginning of the program and are connected with improvement in the rest of the constructs. Satisfaction with life is the variable that is weaker longitudinally, and probably, the recovery of basic levels is related to other fields that are not directly related to communication through SNS.In brief, SNS are presented as a channel of communication, relation, and access to information with a great potency to reinforce individuals emotionally and socially . EveryboTeaching how to use or offering a training course to improve the use of SNS, in this case, Facebook, increases exposure to this type of communication, which has the effect of increasing important indicators of psychological well-being. Contact with people who are important to individuals experiencing homelessness, such as friends and family, is of great value to them, and the contact has significant impact levels when carried out totally or partially through SNS . ProsociConsequently, there is coincidence with other studies as regards the recommendation of providing more public spaces and free and quality Wi-Fi spots to facilitate access to ICT and SNS for individuals experiencing homelessness and other groups facing extreme social exclusion, on the grounds of the multiple benefits associated with internet access ,50.This work has some limitations. First, despite the fact that we have proved that the use of Facebook improves scores in the psychological constructs, we do not know what type of connections and what contents in communication through SNS are the most adequate to improve the well-being of participants, which could be considered a limitation to our work. The second limitation is that our sample was limited and the intervention context is specific, which makes it difficult to extrapolate the results to the group of individuals experiencing homelessness, especially owing to multiple situations, of a highly different nature, which adhere to the concept of homelessness according to the ETHOS classification. Finally, it would be helpful to extend the follow-up period to 6 months.Future lines of research have arisen from this work. First, we consider it interesting trying to replicate this work in different contexts. Second, it would be interesting to assess the effect of job search in individuals experiencing homelessness through SNS, in comparison with specific websites, such as the ones on which our control group proposal is based. Third, the use of mixed designs in which qualitative information can be accessed in parallel with adequate quantitative models is supported, in order to complement the information obtained with the contents of the type of connections that individuals experiencing homelessness maintain.In conclusion, training courses for the use of SNS improve social skills in the internet context, self-esteem, self-efficacy, and satisfaction with life; this improvement continues 4-12 weeks after the intervention. Furthermore, the increase in SNS use that derives from the training course becomes a predictor element of improvement of social skills and self-esteem, the latter having a positive effect on self-efficacy. The increase of these constructs is related to a decrease in individuals experiencing homelessness’ levels of loneliness, isolation, and failure, and therefore, conducting training courses for individuals experiencing homelessness to improve their experience in the use of SNS improves their quality of life and psychological state and is an interesting educational offer for institutions that provide specific services.


A new system for the easy loading and NIR light-triggered release of drugs is introduced. It consists of poly(ε-caprolactone) (PCL) hollow nanoparticles with surface openings containing a biodegradable fatty acid with phase-change ability and a biocompatible photothermal agent. These openings, which can enhance the connectivity between the interior and the exterior, enable the easy loading of drug molecules into the interior voids, and their successive sealing ensures a stable encapsulation of the drug. Upon exposure to an external NIR light irradiation, the photothermal agent generates heat that raises the local temperature of the hollow particles above the melting point of the fatty acid, leading to the formation of nanopores on their shells, and consequently, the instant release of the encapsulated drug molecules through the pores. The synergistic activity of the hyperthermia effect from the photothermal agent and the NIR-triggered release of the drug molecules results in noticeable anticancer efficacy.  Over the past several decades, remarkable progress has been made in the fabrication of polymer nanoparticles (NPs) with a diameter in the range of 1 to 1000 nm for applications in the controlled release and delivery of drugs . In partN-isopropylacrylamide) (PNIPAM) outer shell with independent sensitivity to external pH and temperature  ρHollow + BSAM, where ρHollow is the density of the particle. Based on the values of outerd (1.2 μm) and innerd (0.9 μm) obtained from the TEM image in ρHollow ≈ PCLρ = 1.1 g/mL [BSAM/HollowM × 100) was 1.7%, which was in reasonable agreement with the experimental value of 2.2%. This result suggests that the amount of drug encapsulated in the hollow particles could be readily controlled by varying the concentration of the drug solution for the loading process. In a similar way, we loaded DOX, which is an anticancer drug, into the interior voids of the hollow particles to demonstrate the convenient encapsulation of small molecular drugs  (PCL)/DOX NPs, PCL/ICG/DOX NPs, PCL/FA/DOX NPs, and PCL/FA/ICG/DOX NPs. The diameter, ξ-potential values, and compositions are summarized in We also investigated the release behaviors of FITC-BSA from the four types of hollow NPs, whose diameters, 2 NIR light irradiation led to the instant release of DOX from the hollow NPs, and the release profiles were strongly dependent on the loading content of the FA mixture. The NPs with a loading content of 7.1% achieved 100% release of the drug in 6 h after the NIR irradiation, whereas the ones with a loading content of 14.1% achieved the same result at only 1.5 h since the NIR treatment, which was due to the formation of the larger pores on the shells, as shown in 2 NIR light was irradiated, a noticeable increase in red fluorescence was observed in the nuclei for the cells treated with PCL/FA/ICG/DOX NPs . In the case of the PCL/FA/ICG NPs, the cell viability decreased to 59% because of the hyperthermia effect by the entrapped ICG in response to the NIR light irradiation, while the PCL/FA/ICG/DOX NPs exhibited even more improved anticancer activity under NIR irradiation (viability of 21%). This improvement could be explained by the accumulation of DOX in the nuclei of cells  as well as small molecular drugs (DOX) into the hollow interiors of the NPs, which could be closed for a stable encapsulation of the payloads. When irradiated with an external NIR source, the photothermal conversion by the entrapped ICG raised the local temperature of the hollow NPs above the melting point of the FA mixture, leading to the formation of surface nanopores, and hence the instant release of the encapsulated molecules through them. This NIR light-triggered release allowed the efficient intranuclear accumulation of DOX, resulting in excellent anticancer activity combined with the hyperthermia effect by the photothermal agent. The results suggested that the hollow NPs with NIR light sensitivity are potentially useful in the noninvasive, spatiotemporal control of anticancer drug release for targeted cancer therapy, in conjunction with the NIR light-driven photothermal effect, though further in vitro studies , in vivo studies , and clinical trials are required. Use of the hollow NPs that are capable of an easy loading of macromolecules is applicable to the controlled release of proteins. For biomacromolecular drugs, such as peptides and nucleic acids, that can be crucial in treating various types of cancers, further studies are needed. These studies are currently underway, and the results will be reported in the future.


This paper shows the data of the Flip Teaching and Traditional Methodology on the laboratory practice in two subjects, Physics and Electricity, of a technical degree. The laboratory and final grades of these subjects were shown in four consecutive years. The characteristics of all four years were quite similar, except that the Traditional teaching Methodology (TM) was used in two, while Flip Teaching methodology (FT) was applied in the other two.For further discussion, please refer to the scientific article entitled “Effectiveness of flip teaching on engineering students' performance in the physics lab” [1]. Additional segmentation data in three levels are presented in this data in brief paper. The data is organized in columns where the laboratory and final grade is shown for the two courses and four academic years analysed. Every column header indicates the methodology used, the academic year and the course (Phys for Physics and Elec for Electricity). The “Experimental Design, Materials, and Methods” section explains in more detail how the grades are obtained.The anonymized raw data with the individual grades in the laboratory and final grade in the courses and academic years of reference  are avaiT1), tercile 2 (T2) and tercile 3 (T3) according also to the median of the total grade for the course. In T1/T2) and between tercile 2 and tercile 3 (T2/T3).In Ref.  the data1.1First of all, we present the data grouped by the methodology used, independent of the subject, so joining the Phys TM and Elec TM to make the TM group  and Phys FT and Elec FT to make the FT group (Flip Teaching Methodology group). In 1.2Now, we present the data grouped by the methodology (TM and FT) for the subject of physics. In 1.3Finally, we present the data grouped by the methodology (TM and FT) for the subject of electricity. In 2PoliformaT online teaching platform. The documents and video explained the purpose and the procedure of the experience. An example of the video introducing the free fall practice can be seen at reference [The lab sessions were organized in the four years as follows: before the session the necessary learning material  was made available to students through the eference .The main difference between the two method was that TM involved the teacher explaining the theoretical contents involved and lab procedure before the session, while FT involved the students studying the material in advance (reading the documents and watching videos). They were then expected to start the experience after any doubts had been answered.Lab sessions were based on teamwork. After continuous teacher supervision, the students worked in groups of six. Each group then had ten days to upload a report. The lab report was graded using the rubric supplied in the supplementary data of reference , that waTo obtain the final grade, several items were assessed, with different weights: Traditional exam (70% of the grade), homework and classroom activities (10%) and lab report (20%).


The adsorption of three typical polycyclic aromatic hydrocarbons (PAHs), naphthalene, phenanthrene, and pyrene with different ring numbers, on a common mesoporous material (MCM-41) was simulated based on a well-validated model. The adsorption equilibriums (isotherms), states (angle distributions and density profiles), and interactions  of three PAHs within the mesopores were studied in detail. The results show that the simulated isotherms agreed with previous experimental results. Each of the PAHs with flat molecules showed an adsorption configuration that was parallel to the surface of the pore, in the following order according to the degree of arrangement: pyrene (Pyr) > phenanthrene (Phe) > naphthalene (Nap). In terms of the interaction forces, there were no hydrogen bonds or other strong polar forces between the PAHs and MCM-41, and the O–H bond on the adsorbent surface had a unique angle in relation to the PAH molecular plane. The polarities of different H atoms on the PAHs were roughly the same, while those of the C atoms on the PAHs decreased from the molecular centers to the edges. The increasing area of the π-electron plane on the PAHs with the increasing ring number could lead to stronger adsorption interactions, and thus a shorter distance between the adsorbate and the adsorbent. PAHs,2.5 . In 19762.5 . Low-rin2.5 . The ads2.5 ,13,14. O2.5 ,16. Mast2.5 ,18 and t2.5 .MCM-41 ,22,23 isWith the development of molecular simulation technology, MCM-41 has made great progress in the field of adsorption separation as a typical mesoporous molecular sieve ,29,44,45In this paper, adsorption of the three PAHs Nap, Phe, and Pyr will be simulated based on the grand canonical Monte Carlo (GCMC) method. The potential adsorption mechanism will be discussed based on the adsorption states of the three molecules in the pores.−1) can be determined with the formula:−1) is the molar mass of the adsorbent.It was important to explore the angular distribution of PAH adsorption in the pores since the PAHs exhibited a planar molecular structure. Thus, the adsorption state and configuration of PAHs on the pore surfaces was statistically obtained. Here, the angle between the plane normal vector of the adsorbed PAHs and the axis direction of the cylindrical channel was defined as θ (theta). In order to explain the orientation of the adsorbate molecules in the pores of MCM-41, an order index, S, was defined as follows :(2)S=) is a function of the distance between different particles (molecules or atoms). It is the ratio of the local density to the average density, which indicates the density variation of the particle in space. The RDF method was employed to further analyze the distribution distance between the adsorption sites of the PAHs (rings or atoms) and the active atoms on the adsorbent surface, such as O and H. The RDF between the PAH molecules and different sites of the mesoporous surface is shown in MCM41–CorePAHs) at different positions on the PAHs. The C atoms of the C–H bonds on the PAH were close to H atoms on MCM-41, and C atoms near the center of the PAH were spaced apart from the H atoms on MCM-41. This distribution and action was a result of the positive and negative charges of the molecule. The H and O atoms on the PAHs or the surface of MCM-41 had positive potential and negative potential electrical properties, respectively, while the electrical property of C atoms on the PAHs was dependent on the positions. The central C atom was positively charged while the outer C atom was negatively charged.It can be concluded from the angular distribution and density peak position analysis that the three PAH molecules were adsorbed in a flat position on the inner surface of the adsorbent tunnel. The adsorbates possessed a stable planar structure with H atoms on the molecular edge, and there was no strong polar force generated during the adsorption process that can result in the severe tilt or deflection of the molecular plane. These findings were proved by RDF results, where the hydrogen bonding was weak at the edge of the PAHs from the large distance between H atoms on PAHs and O atoms on MCM-41. Additionally, there was no unique H atom, and the surface generated a prominent force that tilted the PAH plane for the same activity of H atoms at the edge of the PAHs. As we know, the current PAHs were formed by the combination of benzene rings, and large π bonds easily form throughout the molecule. The potential and charge density distributions of Nap, Phe, and Pyr obtained by the DFT simulations, shown in An all-atom model of MCM-41 was established with the carving-out method ,37 basedNap, Phe, and Pyr are typical benzene-ring structures, as shown in −4 kcal mol−1. The cutoff radii for the van der Waals interactions and hydrogen bonds were 15.5 Å and 4.5 Å, respectively. The total step number was 1 × 107, in which the first 5 × 106 steps were used to balance the adsorption state, and the next 5 × 106 steps were used to calculate the state average of the entire ensemble. The PAHs’ gas partial pressure in the simulation was set at a lower level (~100 ppm) according to the common concentration ranges of PAHs in actual situations [In the GCMC simulation, the adsorption temperature was fixed at 398 K, and the adsorbate molecules were regarded as rigid molecules. The Dreiding force field was used to describe the energy forms of the adsorbent–adsorbate and adsorbate–adsorbate interactions. The atomic force field form and interaction parameters are shown in tuations . The fugmax were used to further analyze the adsorption state of the three PAH molecules in the main channel of MCM-41. The adsorption states including the angle distribution and the density peak were analyzed. The radius radial distribution function representative of adsorbate–adsorbent mutual force was finally discussed.The adsorption model results under the pressure of 0.8 PBased on the GCMC simulation, the MCM-41 model was established, and the adsorption of Nap, Phe, and Pyr on MCM-41 was simulated. The adsorption model was validated by use of experimental adsorption isotherms. During the adsorption, no perpendicular state between the PAH molecular plane and the central axis of the adsorbent channel was observed. The order according to the degree of adsorption was: Pyr > Phe > Nap. The three PAHs were adsorbed in a flat position on the surface of the pore, and the configuration planes of Phe and Pyr were more parallel to the surface compared to Nap. The RDF curves indicated that there was no hydrogen bonding produced during the adsorption process. The H atoms in the same PAHs had the same activity, but the adsorption activity of the C atoms decreased from the central position, and the O–H bond on the adsorbent surface had a unique angle with the plane of the PAHs. The area of action of the π-electron plane increased when the number of rings increased, leading to enhanced, stronger adsorption, and thus, a shorter distance between the adsorbate and adsorbent.


The buried penis, if not treated before adolescence, will lead to psychological and physical disorders in adulthood. Therefore, early surgical intervention is necessary. At present, the common surgical methods include the penile corpus fixation, the Johnson's operation, the Devine's method, the modified Devine's method, Shiraki's method, etc. However, we found that these traditional surgeries showed various postoperative complications, such as long-term prepuce edema, avascular necrosis of skin flaps, stenotic prepuce, scarring, and poor appearance. This video shows the main technical steps of our innovative surgical procedure “Six Stitch” (SS) method for the buried penis.The designation of the so-called SS method was based on the total knots made (six knots were made for the SS procedure).st knot). The same procedure was used for the 10 o'clock position (the 2nd knot); At the 2 o'clock position, the skin and subcutaneous tissue at the pubic mound were sutured to the prepubic ligament to reconstruct the appearance of dorsum penis (the 3rd knot). The same procedures were used for the 10 o'clock position (the 4th knot). At the 5 o'clock position, the ventral albuginea was sutured to the tunica dartos and subcutaneous tissue at the penoscrotal junction to reconstruct the penoscrotal angle (the 5th knot). The same procedures were used for the 4 o'clock position (the 6th knot). Finally, the gloved prepuce was reset and circumcision was conducted if the redundant prepuce existed.After the crura penis was fully exposed via a longitudinal incision at the penoscrotal junction, at the 2 o'clock position (around the penis), the superficial layer of albuginea of the crura penis was sutured to the prepubic ligament with 2-0 non-absorbable sutures to prevent the retraction of the penis , which was much longer than the outcome of the above-mentioned methods. Mean operative time was 62.3 ± 12.1 minutes, and there was no serious intraoperative or postoperative complication (only 2 presented scar hyperplasia at the incision site).In conclusion, after the SS procedure, patients with buried penis can acquire an almost 4 cm improvement of penile length and covert incision at the midline of the scrotum, with an acceptable and low incidence of adverse events. This safe and effective procedure may be a viable option for the surgical management of pediatric and adult buried penis.


In this work, SiC and Cu particles were utilized to enhance the thermal and mechanical properties of Al matrix composites. The ball-milling and cold-compact methods were applied to prepare Al matrix composites, and the uniform distribution of SiC and Cu particles in the composite confirms the validity of our preparation method. After characterizing the thermal conductivity and the compressibility of the prepared composites, results show that small particles have a higher potential to improve compressibility than large particles, which is attributed to the size effect of elastic modulus. The addition of SiC to the Al matrix will improve the compressibility behavior of Al matrix composites, and the compressibility can be enhanced by 100% when SiC content is increased from 0 to 30%. However, the addition of SiC particles has a negative effect on thermal conductivity because of the low thermal conductivity of SiC particles. The addition of Cu particles to Al-SiC MMCs could further slightly improve the compressibility behavior of Al-SiC/Cu MMCs, while the thermal conductivity could be enhanced by about 100% when the Cu content was increased from 0 to 30%. To meet the need for low density and high thermal conductivity in applications, it is more desirable to enhance the specific thermal conductivity by enlarging the preparation pressure and/or sintering temperature. This work is expected to supply some information for preparing Al matrix composites with low density but high thermal conductivity and high compressibility. In the preparation of MMCs, aluminum (Al) is an ideal matrix candidate because of its low melting point, high specific strength, and high thermal conductivity ,2,3,4,5.operties ,11,12,13operties  reportedoperties ,16. Choioperties  found thoperties  studied operties  preparedAlthough a lot of work has been focused on the mechanical properties of Al-based MMCs ,20,21,22In this work, the effect of the addition of nanometers and micrometers of SiC and Cu on the thermal conductivity and compressibility of Al MMCs was studied. High-energy ball milling was used to prepare the Al MMC powder, and then the Al MMC powder was pressed into MMCs by cold compaction, which was able to produce the widest range of powder metallurgy engineering materials for studying the compressibility of the Al MMCs. The hot-wire method was used to measure the thermal conductivity of the Al MMCs in order to study the effect of SiC and Cu additions on thermal conductivity. Finally, methods to increase the specific thermal conductivity of Al MMCs are proposed.Two different diameters (500 nm and 1 μm) of Al, β-SiC (SiC) and Cu particle powders commercially obtained from Beijing DK Nano Technology Co., Ltd were used as raw materials for MMC preparation. The sizes of the particles were estimated from the SEM image using ‘Image J’ software, and the estimated sizes follow a Gaussian distribution, as shown in q is the electric heating power per unit length, and The microstructures of the Al MMCs were observed by field-emission scanning electron microscopy (SEM) on a Quanta SU-8820 instrument  with an acceleration of 10 KV. The thermal conductivities of Al MMCs were measured using a commercial device , and were established based on the hot-wire method. The working principle of the hot-wire method is schematically shown in us works ,40,41.3 kg/m3, SiC was taken to be 3.2 × 103 kg/m3, and Cu was taken to be 8.9 × 103 kg/m3. The porosity uncertainty was less than 0.001 in this work.The relative density of Al MMCs can be obtained by the mass-volume method. The mass was measured by an electronic balance with a measurement accuracy of 0.0001 g, and the volume was calculated by the cross-sectional area multiplied by the thickness, where the cross-sectional area is equal to that of the mold, and the thickness was measured using a spiral micrometer with an accuracy of 0.001 mm. For each sample, 10 different measurements were taken to calculate an average thickness. The relative density of MMCs can be calculated by dividing the bed density by the density of the raw particles, where the density of Al was taken to be 2.7 × 10Given the important influence of particle distribution in MMC structures on compressibility and thermal conductivity, the particle distributions in the MMCs are firstly characterized in The diameters and the contents of the raw materials used in the preparation of the Al MMCs are respectively shown in The compressibility curves of Al-SiC MMCs prepared with different pressures are shown in A stands for the plastic deformation of the powder, and B is the density of powder for the case without loading pressure. Parameters A and B can be drawn from A, parameters A and B are further shown in A) decreases with increasing SiC content because of the enhancement of the compression resistance caused by the presence of the hard SiC. Parameter A decreases linearly with increasing content of 500-nm MMC, while the decreasing tendency of A for 1-μm MMC curves up, indicating that the MMCs are more prone to plastic deformation with 500-nm Al nanoparticles than with microscale Al particles, suggesting an obvious size effect for the elastic modulus. A weight fraction of 30% SiC enhances the compressibility, and this is related to the reciprocal of plastic deformation, which is as high as 100% for 500-nm Al MMCs, while a weight fraction of 30% SiC enhances the compressibility only by about 0.4 times for 1-μm Al MMCs, suggesting that small particles have a greater potential to improve compressibility than large particles, which can be attributed to the size effect of the elastic modulus.To estimate the compressibility of powders, the compaction equation developed by Panelli and Ambrosio  was applA) will decrease due to the presence of the hard particles and spherical Cu nanoparticles.Cu particles can be further used to enhance the thermal conductivity of Al-SiC MMCs. The influence of Cu additions on the thermal conductivity and compressibility of Al-SiC/Cu MMCs are shown in Further addition of Cu into Al-SiC further enhances the thermal conductivity, as illustrated in Although adding Cu can improve the compressive properties and thermal conductivity of Al MMCs, the density of MMCs could also be increased due to Cu having a higher density than Al, which may limit its application. Specific thermal conductivity, which is the ratio of thermal conductivity to mass density, can be used to evaluate the effect of Cu content on these two competition properties . In this section, a sintering treatment is applied in order to increase the specific thermal conductivity of Al MMCs.The effects of sintering temperature on the thermal conductivities of Al MMCs are shown in (1)A weight fraction of 30% SiC was able to enhance the compressibility by as much as 100% for 500-nm Al MMCs, while a weight fraction of 30% SiC was only able to enhance the compressibility by about 0.4 times for 1-μm Al MMCs, suggesting that small particles have greater potential to improve compressibility than large particles, which can be attributed to the size effect of the elastic modulus. This enhanced compressibility is a result not only of the high hardness and deformation resistance of SiC, but also of the fragmented SiC particles in the milling process, which may lead to high local internal strains in composites. The thermal conductivity of Al-SiC MMCs will decrease with increasing weight fractions of SiC. This can be explained by the fact that the heat carrier for SiC is phonons, which are able to be scattered by smaller sizes.(2)Adding Cu particles to Al-SiC MMCs improved the compressibility behavior of Al-SiC/Cu MMCs. The enhanced compressibility is a result of the high hardness, high deformation resistance, and the spherical shape of copper nanoparticles, which are able to greatly reduce the contact area between adjacent particles. The thermal conductivity could be enhanced by 100% with an increase in Cu content from 0 to 30%. To meet the need for low density and high thermal conductivity in applications, it is more desirable to enhance the specific thermal conductivity by enlarging the preparation pressure or/and sintering temperature.In this work, utilization of SiC and Cu to enhance the thermal and mechanical properties of Al matrix composites was studied. Firstly, four different weight fractions of SiC were applied in the preparation of Al-SiC powders, and three different weight fractions of Cu were used in the preparation of Al-SiC/Cu powders by ball milling. Subsequently, cold compaction was used to prepare the Al MMCs. The distributions of SiC and Cu in Al MMCs, as characterized by SEM and IR images, confirmed that our ball milling method resulted in homogeneous distributions of SiC and Cu. The mechanical and thermal conductivity measurements revealed that:


The process parameters of a specific reaction chamber model were analyzed based on the computational fluid dynamics method. This study also presents an accurate prediction of the flow regime in the reactor chamber under any operating conditions, without additional experiments, based on an analysis of a great quantity of simulation data. Such research is also significant for selecting the growth parameters relevant to production, providing a specific process growth window, narrowing the debugging scope, and providing a theoretical basis for the development of MOCVD equipment and process debugging.The parameters for metal-organic chemical vapor deposition (MOCVD) processes significantly influence the properties of ZnO films, especially the flow stability of the chamber, which is caused by process parameters such as the shape of reaction chamber, the working pressure, the growth temperature, the susceptor rotational speed, the gas flow rate, and the nature of the carrier gas at inlet temperature. These parameters are the preconditions for the formation of high-quality film. Therefore, this study uses Ar as a carrier gas, diethylzinc (DEZn) as a Zn source, and H Zinc oxide is a wide-bandgap compound semiconductor material with excellent photoelectric properties ,2,3. As To make ZnO-based optoelectronic devices widely used, it is necessary to find high quality repeatable epitaxial film and hetero-structure growth technology. Because of the abundant sources of ZnO and the low growth temperature required, researchers have been able to grow and dope thin films by various methods for a long time. In terms of material quality, pulse laser deposition (PLD), molecular beam epitaxy (MBE), atomic layer deposition (ALD), and metal-organic chemical vapor deposition (MOCVD) have strong competitiveness ,14,15,163 on the base surface was studied using the orthogonal test method. The TMG:NH3 content on the base surface was the main gas group that determined the growth rate and uniformity, and the growth rate increased as the total gas flow rate increased. An increase in nozzle height and inlet gas temperature showed that the film would be more uniform with a lower gas flow rate and higher inlet gas temperature.The unique gas path design of a MOCVD reaction chamber makes the flow of gas complicated and invisible. Traditional design methods have become inadequate due to the cost of manpower, material resources, and time. Simulation has become a powerful tool with which to design a reaction chamber. GaN-MOCVD equipment has developed rapidly due to the wide application of GaN and other III-V materials and mature research mechanisms ,24,25,26There are few studies on the mechanisms of ZnO and 2–6 other II–VI oxide materials because they were developed recently, therefore, the development of oxide MOCVD equipment has been greatly limited ,39,40,41The growth of ZnO film by MOCVD is a complex process that contains heat transfer, fluid flow, mass diffusion and chemical reactions. The following equations of continuity, momentum, energy and species transport in the work are expressed by Equations (1)–(5) ,34,40. as sources for ZnO growth in a typical MOCVD process. The metal-organic precursor was DEZn and the oxygen source was H2O. The gases were injected from the showerhead to the chamber. Complex gas-phase and surface chemical reactions produced several intermediate products. We investigated the reaction mechanisms in detail in previous research [We used DEZn and oxygen kThe growth rate of the film is determined by two factors ,43: The ectively .In the process of growing ZnO thin films by MOCVD, to obtain the required characteristic films, the process parameters are mainly dependent on the gas inlet flow rate, inlet gas temperature, substrate growth temperature, base rotation speed, and cavity pressure. As shown in The characteristic dimensionless number array is used to describe the phenomena of gas crystal growth and transport as shown below.The relationship between pressure and rotational speed was studied under the conditions of fixed flow rate, inlet temperature and substrate temperature. When the speed was fixed, the pressure gradually increased. When the cavity becomes unstable, the pressure is the critical flow pressure. The critical pressure points were determined by a series of rotational speeds, and the steady flow curves were fitted. The flow below the curve is stable and the flow above the curve is unstable. The whole speed range can be approximately divided into three regions: In low-speed region A1  was 673 K, and the inlet gas temperature was Tin = 300 K. According to the principle of stability determination, the pressure and speed were adjusted to determine the P-ω stability map. The simulation results under different inlet flow rates were processed according to the stability principle, based on the stability judgment method shown in The substrate temperature of the reaction chamber (T(1) With the increase in the gas inlet flow rate, the critical operating pressure in the corresponding curved areas changed significantly. The curve with the large flow rate is above the curve with the small flow rate. Because increasing the Re value increases the reaction gas flow, forced convection increases from top to bottom, and the buoyancy and rotational flow are restrained. That is to say, a wider pressure growth window was needed to maintain stability under a larger gas inlet flow rate, and the range of operating pressure also increased when the rotational speed of the base was the same.(2) With the increase in the gas inlet flow rate, the corresponding critical operating pressures A1, A2, and A3 have corresponding changes in the speed range. The rotational speed of the A1 region gradually decreased with the increase of the gas inlet flow rate, and the change in the critical pressure value was relatively small. The rotational speed of the A2 region increased with the increase in the gas inlet flow rate. For a rotational speed ranging from 100 rpm to 300 rpm, the maximum allowable pressure can be obtained by translating the peak value of the operating pressure to the right, and the slope of the curve in this region is larger. It can be seen that the critical pressure of the stable point varied greatly when the inlet flow rate was increased. The rotational speed in the C region decreased with an increase in the gas inlet flow and the rate of change of critical pressure decreased. The increase in gas flow mainly affected regions A2 and A3, and the influence on region A1 was relatively weak.susceptor) was 673 K and the gas inlet flow rate was Q = 13 slm. The P-ω stability map of Tin with different inlet temperatures was determined by adjusting the pressure and rotational speed according to the principle of stability determination. According to the stability principle, the simulation results of different inlet temperatures can be fit to four extreme value curves of stable points, as shown in The temperature of the reaction chamber base (T(1) With the increase in the inlet gas temperature, the maximum pressure required for maintaining the stability of the flow field in the reaction chamber increases. The velocity increases with the increase in the inlet gas temperature, and forced convection from top to bottom increases, which restrains the buoyancy and rotational flow. The curve of high inlet temperature is above the curve of low inlet temperature. When the inlet temperature was increased, (2) With the increase in the inlet gas temperature, the corresponding critical operating pressures in the A1, A2, and A3 regions experienced some changes in their speed range. The rotational speed in the A1 region gradually decreased with the increase in the inlet gas temperature, and the change in critical pressure is obvious. The rotational speed in the A2 region gradually decreased with the increase in the inlet gas temperature. For a rotational speed varying from 200 rpm to 300 rpm, the peak pressure during the operation shifts to the left to obtain the maximum allowable pressure. The slope of the curve increased, that is, the inlet gas temperature increased and the rate of change in the critical pressure was greater. The rotational speed in the A3 region increased with the increase in the inlet temperature. It can be seen that an increase in the inlet gas temperature mainly affected the A1 and A2 regions, while the effect on the A3 region was relatively weak.in) to 300 K and the gas inlet flow (Q) to 13 slm at different base temperatures, respectively, the P-ω diagram was determined by adjusting the pressure and rotational speed according to the principle of stability determination. The simulation results at different substrate temperatures are based on the stability principle, which is based on the processing method shown in By setting the reaction chamber inlet temperature (T(1) With the increase in the substrate growth temperature, the maximum pressure required to maintain field stability was smaller. As the substrate gas temperature increased, the thermal buoyancy increased with the increase in (2) With the increase in substrate temperature, there were some changes in the speed range of the critical operating pressure in the A1, A2, and A3 regions. The rotational speed in the A1 region decreased with the increase in substrate temperature, and the change in the critical pressure value is more obvious. The rotational speed in the A2 region increased with the increase in substrate temperature. From 200 rpm to 400 rmp, the maximum allowable pressure can be obtained by translating the peak value of the operating pressure to the right, and the slope of the curve in this area increases. It can be seen that when the substrate growth temperature decreased, the rate of change in the critical pressure of the stable point was larger. The rotational speed in the A3 region decreased with an increase in substrate temperature, and the rate of change in the critical pressure for increasing rotational speed remained basically unchanged. It can be seen that increasing the substrate temperature mainly affected the A1 and A2 regions but had little effect on high-speed regions, such as the A3 region.2O, the large-scale P-ω stability maps were established through high-speed rotating disc reactions. The growth window of ZnO-MOCVD can be enlarged by increasing the inlet gas flow rate and inlet gas temperature and decreasing the substrate growth temperature. With a decrease in the inlet flow rate and an increase in the substrate temperature and inlet gas temperature, the speed regulation range in the A2 region decreases. With a decrease in the inlet flow rate and an increase in the substrate temperature and gas inlet temperature, the speed regulation range in the A3 region increases. The A1 region is less affected by the change in process parameters. This theory has played a guiding role in the growth and debugging of MB-600D ZnO-MOCVD by technicians and the development of good ZnO epitaxial films.Using MD600B ZnO-MOCVD as the prototype machine and the transport-reaction model of ZnO growth by DEZn and H


Implemented in Python, the software is based on the template matching method and computes the 2D displacements and strains of samples subjected to mechanical loading. In this work, the potentialities of py2DIC were evaluated by processing two different sets of experimental data and comparing the results with other three well known DIC software packages Ncorr, Vic-2D and DICe. Moreover, an accuracy assessment was performed comparing the results with the values independently measured by a strain gauge fixed on one of the samples. The results demonstrate the possibility of successfully characterizing the deformation mechanism of the investigated materials, highlighting the pros and cons of each software package.Thanks to the advances in computer power, memory storage and the availability of low-cost and high resolution digital cameras, Digital Image Correlation (DIC) is currently one of the most used optical and non-contact techniques for measuring material deformations. A free and open source 2D DIC software, named  The last few decades have been characterized by a continuous development of non-contact measurement techniques for displacement and deformation estimation ,4,5,6,7.DIC can be performed in two (2D) or three (3D or stereo DIC) dimensions. The 2D DIC employs a single fixed camera and estimates displacements and deformations in a selected plane. Thus, 2D DIC is appropriate and useful only when the displacement and strain fields can be considered plane within the Area Of Interest (AOI). In this case, the image plane and the plane where deformations are estimated should be kept parallel and fixed during the acquisition of all the images, even if it has to be underlined that even significant misalignments up to 5 degrees with respect to this parallelism condition have a very small impact (within 0.5%) on the estimated displacements . AlternaFrom an algorithmic point of view, subset-based DIC  and finite element-based DIC  are the two most commonly implemented approaches ,9. Localpy2DIC, was developed at the Geodesy and Geomatics Division of the Sapienza University of Rome (http://github.com/Geod-Geom/py2DIC/). Implemented in Python, the software can estimate 2D displacement and strain fields from an input set of images.Nowadays, several DIC software solutions are available, both commercial and open source see . Howeverpy2DIC potentialities were evaluated. In particular, two different sets of experimental images were processed to estimate displacement and strain fields; the accuracy of the results was evaluated by comparing the estimated displacements with those computed from the strain values independently measured by a strain gauge fixed to one of the samples. Furthermore, the obtained displacements were also compared with those obtained through three renowned software applications: the well-known and mature open source software packages Ncorr and DICe and the commercial software Vic-2D, developed and sold by Correlated Solutions Inc, USA.In this paper, by continuing the work started in References ,13, py2Dpy2DIC in detail; The paper is organized as follows: Ncorr , DICe  and YaDICs  are among the most popular ones : are generated following the approach described in Reference . FinallyThe analysis is repeated for different pairs of images captured at different temporal steps: the results are the accumulated displacement and strain fields for each pair of the processed images.py2DIC, two different examples were processed.To investigate the potentialities of py2DIC, Ncorr, Vic-2D and DICe, the “plate hole” sample images (Sample 12) from SEM DIC challenge were analysed. Sample 12 is an experimental set of 12 images (resolution of 400 × 1040 pixels) of a steel plate with a hole in the middle being loaded in tension  2D-DIC challenge simulated datasets ,39  specimens obtained from GFRP beams. The specimen dimensions are reported in During the campaign the specimen was subjected to tensile test by means of a servo-hydraulic universal testing machine . The test involved placing the GFRP specimen in the grips of the testing machine and slowly extending it until failure. Specifically, the upper part of the specimen was fixed to two steel crossheads and the pull load was applied at the bottom part of the specimen using a displacement-control protocol system (0.5 mm/min). During the process the elongation of the gauge section was recorded against the applied force. A metric reference was used to calculate the pixel dimension necessary to perform the conversion pixels-to-unit length for the measured displacement fields. In order to measure the specimen local deformations, vertical and horizontal standard strain gauges were fixed on the sample surface, where no speckle pattern was applied . Indeed,Furthermore, a Canon EOS 1200D camera  was placed around 20 centimetres far from the sample on a metallic bar fixed over two tripods to avoid vibrations during the loading tests. The camera was connected to a standard laptop and the EOS Digital Solution Disk Software 31.4A  was used to acquire images with a time sampling of one acquisition every 5 s and a resolution of py2DIC was validated using the two mentioned sets of images which were processed to obtain horizontal (u) and vertical (v) displacement fields. For the first image set, also the Green Lagrangian strain fields  computed with py2DIC and those obtained with each of the compared software were also calculated as follows:i and j are the row and column pixel locations, respectively.LE68: Linear error with 68% of probabilityLE95: Linear error with 95% of probabilityReferring to displacement differences Equation ), a globu and v displacement values obtained from py2DIC, Ncorr, Vic-2D and DICe were plotted along vertical sections.Finally, in order to examine the results more closely, the py2DIC results were calculated at every pixel of the considered images, using a u and v displacement computation respectively.The first and the last image of the experimental set with a resolution of py2DIC and Ncorr comparison was performed; the obtained displacement fields are shown in Ncorr returned the displacements on a 2-pixel spaced grid.Firstly, the Regarding this comparison, the results are in reasonable agreement with each other. In fact, starting from the displacement differences of the two software, the above mentioned statistical parameters were computed and they are reported in py2DIC and Vic-2D were analyzed. Vic-2D returned the displacements for every pixel of the considered images, as for py2DIC.Secondly, the differences between the displacements computed using py2DIC on the vertical displacements. Furthermore, it is highlighted in Vic-2D is not able to compute the displacements near the hole and this is probably due to the handling of the Nan values.The obtained displacement fields are shown in py2DIC results were compared with those obtained using DICe in terms of displacement fields .For the tensile test image pair, a local approach was used for py2DIC horizontal and vertical displacements were computed using a Ncorr, Vic-2D and DICe. In particular, the results from the DICe FE approach were interpolated on a regular grid to facilitate the comparison with py2DIC. The obtained displacement maps are reported in py2DIC, Vic-2D and DICe returned the displacements for every pixel, while Ncorr computed the displacements on a 2-pixel spaced grid. Ncorr, Vic-2D and DICe in terms of statistical parameters.Specifically, u and v displacements computed by py2DIC and those generated using Ncorr, Vic-2D and DICe. Neither biases, no outliers were highlighted and again a normal distribution of the differences was found. Also, the analysis of the values of the statistical parameters highlights few microns agreement with respect to all the compared software applications. Moreover, also in this case, the comparison is slightly worse for what regards the vertical displacements. Finally, the vertical section comparisons show how software displacements are in good agreement with each other even if, in this case, the adoption of DICe global approach leads to slightly different results.Also for this set of images, it is possible to observe a very good correspondence between the py2DIC results were also compared to strain gauge measurements. Specifically, a strain gauge was placed horizontally on the sample side facing the camera, as shown in py2DIC displacements were calculated and spatially averaged on the points corresponding to the left and right extremities of the device.For the tensile test of the GFRP sample, py2DIC displacements well follow the strain gauge reference trend: the RMSE of py2DIC displacements computed with respect to the strain gauge measurements is of the order of some microns [Then, since the sample central section was covered by the wires of the strain gauge, the difference between the displacements observed in these two positions was calculated at the bottom and top part of the strain gauge, respectively . Finally microns .py2DIC, a free and open source 2D DIC software was developed at the Geodesy and Geomatics Division of the Sapienza University of Rome. The potentialities of the developed software were investigated by processing two different sets of experimental images and comparing the results with those supplied by the three well known software packages, one commercial (Vic-2D) and two free and open source (Ncorr and DICe) and with those coming from independent measurements by a strain gauge fixed on one of the samples. The first set of images was selected from the SEM DIC challenge simulated datasets; the second one was acquired during an experimental campaign performed in collaboration with the Lab of Structural Engineering of the Sapienza University of Rome and it is available at http://github.com/Geod-Geom/py2DIC/tree/master/LabTest together with the strain gauge measurements. The obtained results point out the very good py2DIC performances in successfully characterizing the deformation mechanism of material subjected to mechanical loading: the new software is indeed able to estimate displacements with an agreement at the level of few hundredths of a pixel or few microns; also, the compared strain fields are globally consistent, even if in this case only a graphical comparison was possible, since each software adopts a proper grid. In conclusion, py2DIC represents a reliable free and open source alternative software for 2D DIC applications in the field of solid mechanics.py2DIC outside the elementary lab conditions, in order to bring the methodology and the software at a full 2D operational level in the widest practical cases, releasing as much as possible the acquisition constraints related to the testing setup. Furthermore, it would be worth implementing the 3D DIC method, to also characterize the 3D deformations which can occur during the loading tests. Finally, in order to increase the computational efficiency of the software, a pyramidal oversampling approach will be implemented, along with a multi-threaded computation of the displacements over all the staggered grids.In the future, this research project will aim to investigate the potentialities of References


The pH and chemical compositions of the condensed liquid that adhered to the tower’s inner face and the macromorphology, compressive strength, and neutralization depth of in situ specimens were tested periodically. In addition, a finite element numerical simulation was conducted to simulate and verify the concentration distributions of CO2 and SO2 in the flue gas in the cooling tower. The results showed that the cleaned flue gas was enveloped, diluted, and uplifted by hot vapor in the cooling tower, and its concentration decreased. Meanwhile, the effective diffusion radius increased gradually as the flue gas rose. With the same elevation in the cooling tower, the concentration of flue gas decreased rapidly from the central point to the surrounding area. The air near the inner surface of the cooling tower was merely dampened air with a low concentration of acidic gas due to the gigantic diameter of the cooling tower. As a result, the injection of cleaned flue gas will not evidently increase the corrosion risk in a natural draft concrete cooling tower.The article undertakes the very important topic of the long-term durability of concrete in a natural draft concrete cooling tower with flue gas injection. The corrosive conditions, including temperature, relative humidity, and CO The flu treated ,3. Washi treated ,5. Howev treated ,3. Howev treated ,7.x and NOx remain in the cleaned flue gas [The inner surface of the tower wall is attacked chemically by low-concentration acid vapor because residues of SOflue gas ,3. The cflue gas ,9. Howevflue gas ,11. Contflue gas ,4.The cooling tower is an essential component of coal-fired power plants, and its structural safety and long-term durability have been the focus of researchers’ attention ,16,17,182. The cooling tower is 150 m high, and the height of the flue gas inlet is 42 m  was used as the background. This project is composed of two 600 MW ultra-supercritical coal-fired units, and the cooling system is a secondary circulation water supply system equipped with a counter-current natural draft cooling tower with an area of 8500 m is 42 m . The conA special C45 acid-resistant concrete was designed in consideration of the potential risk of acid attack and cooling towers’ expected service life of 30 years. The mixture proportion of the designed acid-resistant concrete is shown in 2 and SO2 sensors. The detailed monitoring plan is shown in Health monitoring is an important means to ensure the safety performance of major civil engineering structures ,20,21. S2 and SO2 concentration data were collected with a small data acquisition instrument every half an hour and saved automatically. Generally, the condensate is only observed on the inner wall surface when ambient temperature is below the dew point of vapor in a cooling tower; thus, the condensate in this study was sampled twice in the winter season during the entire monitoring period. The pH and chemical composition of the condensate samples were analyzed with a PHS–25 pH meter  and ISC-1500 ion chromatograph , respectively. In situ concrete specimens were retrieved at the age of 300 and 510 d after power plant operation, and visual appearance, compressive strength, and neutralization depth were observed or tested.Temperature, relative humidity, and COAccording to the measured data, the temperatures near the inner surface of the cooling tower were considerably affected by the external environmental temperature and changed regularly with seasons and day and night cycles due to the thin-shell structure of the cooling tower . Generally, the temperatures near the inner wall surface were slightly higher than that of the outside environment. However, the temperature differences between different locations, such as at the tower outlet, tower throat, and tower middle, were small. The moisture contents in a cooling tower are always high, and the moisture transmission resistance in concrete is also high . Therefo2 concentration near the inner surface of the cooling tower over a year is plotted and shown in 2 [2 concentration near the inner surface of the tower showed a low concentration with a range of 350–650 ppm. This value is not considerably different from the CO2 concentration of the ambient atmosphere outside the tower. The concentrations of CO2 at different positions inside the tower, such as the tower outlet, tower throat, and tower middle, also showed no evident differences. The data obtained for SO2 were similar to those for CO2 but with a lower concentration of 0–0.5 ppm. The monitoring results of CO2 and SO2 concentrations indicate that no high concentration of acid gas was present around the inner surface of the cooling tower.On the basis of the measured data, the development of COown in 2 , the CO2− and SO42− ions were slightly higher than those of F− and NO3− ions. However, such low contents basically indicate no evident corrosion risk in concrete [concrete . In sum,Partial specimens were retrieved from the platforms inside the cooling tower, and typical photographs of these specimens are shown in The compressive strengths of the in situ concrete specimens are shown in The neutralization depths of the concrete specimens were determined using a 1% phenolphthalein ethyl alcohol indicator, as shown in The monitoring results of flue gas and the durability performance of the in situ concrete specimens show that the injection of the cleaned flue gas into the cooling tower did not evidently increase the corrosion risk in the cooling tower concrete. As a result, heavy-duty anti-corrosion protection or specially designed concrete is not necessary. Such findings are of great significance for saving costs in the construction and maintenance of a natural draft cooling tower with flue gas injection.2 [2 gas nor a high concentration of CO2 in the monitored data of this study? To answer this question, a finite element method was used to simulate the flow and diffusion of the cleaned flue gas in the cooling tower and to obtain its concentration distribution.Theoretically, the flue gas of coal-fired plants, even after desulfurization treatment, still contains low concentrations of acidic gas and at least high concentrations of CO2 . Why is Fluent is a commonly used software for the simulation of heat and mass transfer in a cooling tower ,25. The According to the original data of the cleaned flue gas provided by Lu’an Power Station, the initial temperature and speed of the flue gas were 48 °C and 15 m/s, respectively. The major composition of the cleaned flue gas is shown in To simulate the concentration diffusion of the flue gas in the cooling tower, which belongs to a transportation process of chemical components, the turbulence model of the k-ε double equation and the species transport model were used ,27. In a2 and SO2 in the cooling tower. The concentration distributions of CO2 and SO2 were similar and imitated a burning candle’s flame, but they had different concentration values. Generally, the concentration of CO2 or SO2 gas at the central point of the tower was the highest, and the concentration decreased gradually as CO2 or SO2 gas rose. The initial concentration of CO2 at the central point was approximately 1.2 × 105 ppm. The value decreased to approximately 1.5 × 104 ppm at the tower outlet.2 and SO2 along the horizontal direction are plotted in Three horizontal positions in the tower middle (70 m), tower throat (110 m), and tower outlet (150 m) were selected to further explore the vertical and radial distributions of flue gas concentration in the cooling tower. The concentration distributions of CO2 or SO2 concentration in the cooling tower were similar to a typical normal distribution curve that exhibits characteristics of a high middle part, low two sides, and symmetric left and right sides. The concentration of CO2 not only decreased as the flue gas rose but also decreased quickly along the horizontal direction. Particularly, at the height of 70 m, the concentration of CO2 at the central point was approximately 4.34 × 104 ppm, whereas the concentration decreased to close to the concentration of CO2 in natural atmosphere when it diffused to the diameter of 24 m. That is, the effective diffusion diameter of CO2 at this height was approximately 24 m. Similarly, the effective diffusion diameters of CO2 at heights of 110 and 150 m were about 28 and 40 m, respectively. These dimensions are all smaller than the corresponding diameter of the cooling tower. In other words, before the flue gas reached the inner surface of the cooling tower, its concentration of CO2 decreased to near the concentration of the natural atmosphere. These findings agree well with the measured CO2 concentration near the inner surface of the cooling tower at different locations.The horizontal distribution curves of CO2 in the cooling tower was similar to that of CO2 but with a lower concentration. By further simulating the flue gas distribution in different seasons, we found that the concentration distribution of flue gas in the cooling tower was hardly affected by seasonal changes.The concentration distribution of SO2 concentrations along the radial direction at the tower outlet were measured to further verify the correctness of the numerical simulation results. Initially, within the range of 0–7.5 m from the edge of the tower, the concentration of CO2 was low, and the values were between 350 and 550 ppm, similar to the concentration of CO2 in external natural atmosphere. Gradually, within the range of 10–15 m from the tower edge, the CO2 concentration increased. When the distance from the tower edge exceeded 17.5 m, the concentration of CO2 increased rapidly. A comparison of the measured data of radial CO2 concentration at the tower outlet and those in the numerical simulation is plotted in Because it is difficult to measure the flue gas concentration inside the cooling tower, the CO2 concentration distribution in the cooling tower exhibited characteristics of a typical normal distribution. Even at the height of 150 m, the CO2 concentration at the tower center was still very high, with a value close to 16,000 ppm. This value is approximately 35 times that of the CO2 concentration in ambient natural atmosphere. However, due to the normal distribution characteristics of the flue gas concentration in the cooling tower, the concentration decreased rapidly as the flue gas diffused to the edge of the cooling tower. The concentration of the flue gas almost dropped to the same level as that in ordinary atmosphere before reaching the tower wall due to the gigantic diameter of a normal cooling tower. Therefore, we conclude that cleaned flue gas discharged from the flue gas tube into the cooling tower does not evidently increase the corrosion risk in the concrete tower wall.The measured data were consistent with the results of the numerical simulation, thereby confirming the correctness of the numerical simulation of flue gas concentration distribution in the cooling tower. The COThe cooling towers in this project have been operating for five years since their completion. The tower concrete still shows no signs of corrosion, which is consistent with the analysis results in this study. The savings in expensive anti-corrosive coatings and specially designed concrete can result in significant cost savings for the construction of cooling towers with flue gas injection.The following conclusions were derived from the field monitoring, experimental investigations, and numerical simulation in this study.The flue gas conditions near the inner surface of a cooling tower are remarkably different from those in the tower center. The flue gas in the tower center has a high concentration of acid gas, whereas that near the inner wall of the cooling tower has a low concentration of acid gas and has almost no corrosion risk.The condensate attached to the inner wall of the cooling tower is slightly acidic, with a pH value ranging from 6.0 to 6.5. It has low contents of corrosive media. The macromorphology, compressive strength, and neutralization depth of the in situ concrete specimens indicate that the condensate attached on the inner wall of the cooling tower poses no strong corrosive risk to the tower concrete.The finite element model established in this study can effectively simulate and predict the concentration distribution of flue gas in a cooling tower. The predicted results are consistent with the measured data. Generally, the concentration of flue gas at the tower center is the highest and decreases rapidly as it leaves the center. Given the gigantic diameter of a cooling tower, the flue gas is not expected to cause a high corrosion risk to the tower concrete.