The regression model that was developed showed that WC (R2 = 47.1%), beyond BF% (R2 = 50.3%) and WHtR (R2 = 50.0%), was a useful measure of CRF, and stronger than BMI (R2 = 45.8%) or WHR (R2 = 39.2%). The risk of obtaining the CRF result classified below a good level (below the percentile range of P60-P80) was significantly higher in children with a larger WC (odds ratio (OR) for the WC change of 1 cm equals 1.14 ). The simplicity of measuring WC and the possibility of using this measurement in the calculation of WHtR with reference to CRF indicate its usefulness in the prophylactic exams of school children.The early identification of modifiable risk factors and their monitoring, also within school physical education (PE) classes, are becoming indispensable in the context of public health. The aim of this study was to test whether making use of waist circumference (WC) measurements increases the possibility of predicting the results of cardiorespiratory fitness (CRF) in school-age children, as compared with body mass index (BMI) and other somatic indicators related to body fat. The cross-sectional study covered 190 children aged 10 to 15 years, participating in school PE classes. Body height (BH), body weight (BW), WC, hip circumference (HC) and percentage of body fat (BF%) were measured. BMI, waist to hip ratio (WHR) and waist to height ratio (WHtR) were calculated, and a CRF test was performed by means of a 20 m shuttle run test (20mSRT). The peak heart rate (HR In studies concerning population health, anthropometric measurements and ratios, including body height (BH) and body weight (BW), body fat (BF), body mass index (BMI), waist to hip ratio (WHR), waist to height ratio (WHtR) and waist circumference (WC), are most commonly used as screening measures , as theyAmong Polish 8-year-olds, 30.7% are overweight or obese; 21.5% are characterized by too large a waist circumference; and 20.8% have an increased systolic blood pressure . In the CRF, whose low level is strongly and independently related to all-cause mortality in adults ,20, is aThe aim of this study was to test whether making use of the WC measurement increases the possibility of predicting CRF results in school children, as compared to the BMI and other somatic indicators related to body fat.The study covered school children within the age group 10–15 years, without any medical contraindications to participating in school PE lessons. The sampling was purposive, and the tests were performed in a school with which the Physical Education Department (WWF) of Rzeszow University (UR) had entered a cooperation agreement. The tests were performed in the school’s venue, in the morning. Prior to the tests, written consent of the school authorities, of the parents or legal guardians and of the children was obtained. The children whose parents did not consent to the tests and those who did have the consent yet were absent on the days of the tests were excluded from the study. The participants of the study were informed about the purpose and the procedure of the trials and measurements. Within the study, anthropometric measurements were taken, and a cardiorespiratory fitness test was performed. Ultimately, 190 school children (41.6% of whom were boys and 58.4% were girls) participated in the tests. The age of the tested children was determined based on the information provided by the parents. The study was conducted in 2017 with the approval of the Rzeszow University bioethics committee (No. 1/06/2014). In accordance with the measuring protocol adopted, body height was measured by means of the Seca 213 stadiometer  with accuracy to 0.1 cm. Body weight and BF% were determined through an electrical bioimpedance analysis with the use of the Tanita TBF 300 : a body composition analyzer. These measurements also provided information on the BMI expressed as BW (kg)/BH squared (m). The BMI was classified according to WHO criteria . Waist cThe cardiorespiratory fitness was assessed on the basis of the 20 m shuttle run test . The tesThe starting speed of the run was 8.5 km/h, and it was increased by 0.5 km/h with each stage. The tested person was supposed to move in such a way as to be at one of the two ends of the 20 m line at the moment of hearing the signal. In the case of school-aged children, it is recommended that they run with a leader—a pacemaker—who helps them to keep up with the audio signals. This recommendation was followed in our study. The aim of the trial was for the participant to maintain the set rhythm for as long as possible. The result of the test was the number of fully completed 20 m laps. The trial was terminated the moment the participant failed to maintain the imposed rhythm twice in a row or declared himself/herself unable to continue. peak; beats per minute) was established by means of the Polar Team2 system .All the participants were provided with identical conditions and the test was conducted in the school sports hall. At the end of the 20 m shuttle test, the peak heart rate of the children  age was treated as a quantitative variable. R2). For example, for one-way comparisons of CRF centile classifications among girls and boys, and with respect to age, the Mann–Whitney test was used, alongside Spearman’s rank correlation coefficient. A logistic regression model was also created, by means of which the influence of WC on the probability of the occurrence of the CRF value classified below the good level (P60–P80 = good) was assessed. The results of the logistic regression analysis were presented by means of an odds ratio (OR). In the interpretation of the results, the values of p ≤ 0.05 were considered as statistically significant. All analyses were performed in the Statistica 13.3 software .In the descriptive statistics of the variables, arithmetic means (M) were used, together with standard deviations (SD) as well as minimum (Min) and maximum (Max) values. In order to determine correlations between the somatic indicators and the results of the cardiorespiratory fitness test, a regression analysis was applied. Five models were created, in which each of the somatic indicators  was consecutively introduced as an independent variable. The models also considered sex and age. Comparisons of the predictive value of particular somatic indicators were made on the basis of the coefficient of determination . They were also significantly varied with respect to the age (p < 0.001). Based on the value of regression coefficients it can be noted that, on average, the number of laps covered by the boys was higher than that of the girls by 17.4. Furthermore, with each year of age, the results of the school children increased by 4.4 laps  viewed as the number of laps covered were significantly higher among the boys (4.4 laps .p = 0.643), it can be said that with reference to the centile norms adopted from Tomkinson, the CRF of the boys and the girls was at a similar level. Most results obtained by the school children were at least at an average level. It was also verified how correlated the CRF classification was to age: for that purpose, the values of Spearman’s rank correlation coefficient were calculated. A statistically significant, yet weak, correlation between the fitness level and the age existed in the group of girls (rS = 0.28).Next, considering sex and age, the numbers of laps run were classified into the 7-point adjective scale and presented for the whole cohort and separately for the girls and for the boys . On the The above-presented analyses suggest that the number of laps is influenced by the sex and the age of the school children; hence, five separate regression models were created in which the number of laps was a dependent variable while sex, age and, in turn, each of the considered somatic indicators BMI, BF%, WC, WHR and WHtR were the independent factors.R2) for each of the models . All of the models were statistically significant, and their predictive value was very similar: the coefficient of determination ranged between 39.2 and 50.3%.R2 = 47.1%), alongside BF% (R2 = 50.3%) and WHtR (R2 = 50.0%), was a useful measure of CRF, and stronger than BMI (R2 = 45.8%) or WHR (R2 = 39.2%).The regression model that was developed showed that WC . That means that 1 cm of waist circumference translated, on average, into the increase in the risk of the occurrence of CRF below the good level by 14%. In the case of a difference in the waist circumference of 5 cm, the increase in the risk of being in the CRF group at the level below the good one was almost twofold (1.145 = 1.92), and with 10 cm of the difference, this increase was nearly fourfold (1.1410 = 3.70).Among the tested school children, a group was singled out in which CRF results (number of laps) were classified below the good level (below P60–P80). Next, a logistic regression analysis was applied to estimate the odds ratio (OR) for the occurrence of CRF below the good level with the WC change of 1 cm. The OR value amounted to 1.14 .It is emphasized that the measurement of WC is the simplest, and at the same time, the most effective measure of truncal obesity in children and adolescents in comparison with WHR . In our R2 = 47.1%) and WHtR (R2 = 50.3%) was close to the predictive value of the BF% (R2 = 50.3%) estimated by means of bioimpedance. In addition, in other studies comprising children, significant correlates of BF and WC were noticed [It is more and more often suggested that it is WHtR that can be a more effective indicator of ‘early health risks’ related to central obesity . WHtR is noticed .The condition of CRF in the population of children and adolescents may help to predict future diseases, including heart diseases, cancers, chronic respiratory diseases or diabetes . A revieAs other authors point out, school may play an important role in identifying children with a lower level of physical fitness ,30. The Rollo et al. (2022) note that currently there is too broad a range of health-related cut-points with reference to CRF among adolescents to indicate universal thresholds specific to age and sex . Similarpeak at the end of the test, which implies that not only the school children who are more physically active were motivated to do the test. What is more, to the best of our knowledge, little research is available covering the population of Polish children, which would take into consideration in one study (such as in our research) the results of CRF with reference to several, commonly used, simple screening measures for the health of the population. For example, in one big Polish population study on children and adolescents, the 20 m shuttle run test was performed within the Eurofit test, but only BH and BW were measured and BMI calculated [In our opinion, a strong point of this study consists of the fact that the participants performed the 20 m shuttle test with full commitment, which can be proved by the high mean values of HRlculated . On the lculated .The limitation of this study is the relatively small population of children from one school, which still allowed for the adopted CRF classification to be represented by both sexes in all the adopted centile CRF categories except for the ‘very poor’ one. However, due to its cross-sectional character, this study cannot determine the causality of the relation between CRF and the anthropometric indicators, hence the need for further longitudinal studies covering a bigger sample. Despite its limitations, the value of our study was to provide relevant data on the health of school-aged children.It has been shown that waist circumference, alongside BF% and WHtR, is a useful CRF predictor. Additionally, it has been demonstrated that somatic indices related to BF%, except for WHR, were stronger CRF predictors than BMI, which confirm the claim that BMI should not be the only index used. WC measurement allows the additional usage of its result for calculating WHtR, whose predictive value with respect to CRF was, in our study, at the level of BF% measured by means of BIA, which indicates its usefulness in the prophylactic exams of school children.


The larval indices and dengue morbidity were diminished and related to the nine themes present in the community leaders’ reflections and to the satisfaction of the community members. Hence, local administrative organizations should use community-based approaches as the subdistrict dengue solution innovation to reduce the dengue problem.The purpose of this study was to evaluate the effects of developing and using a model to predict dengue risk in villages and of a larval indices surveillance system for 2372 households in 10 Thai villages. A community participatory action research method was used in five steps: (1) community preparation covering all stakeholders, (2) assessment of the understanding of a dengue solution and a larval indices surveillance system, (3) development of a prediction and intervention model for dengue risk villages, (4) implementation of the model that responds to all stakeholders, and (5) evaluation of the effects of using the model. The questionnaires to assess and evaluate were validated and reliability tested. The chi-square test and Fisher’s exact test were used to analyze the quantitative data collected by means of questionnaires. Thematic analysis was applied to the qualitative data collected through interviews. The results found that the model consisted of six main activities, including (1) setting team leader responsibility, (2) situation assessment, (3) prediction of the dengue risk in villages, (4) the six steps of the larval indices surveillance system, (5) the understanding of the dengue solution and the understanding of the larval indices surveillance system training program, and (6) local wisdom innovation. The effects of using the model showed a statistically significant increase in correct understanding among 932 family leaders, 109 village health volunteers, and 59 student leaders regarding dengue prevention and control ( Dengue is a critical health problem in tropical and subtropical regions, especially in Southeast Asia ,2, and hThe SAOs may be able to tackle dengue and reduce mosquito breeding grounds, but the research also found that they need to integrate other strategies for implementing the ordinances ,6. One sThese results denote that the SAOs should be engaged in developing and implementing activities to achieve community-based solutions for dengue ,17. ThisThen, by the SAO model, the local health teams implemented interventions, such as health education for stakeholders to better understand dengue and to develop distinctive and cutting-edge strategies for preventing mosquito bites; these comprised ten villages, three temples, five schools, four child development centers, and two primary care units, which were representative of 2372 households. There were 134 village health volunteers (VHVs). The dengue mortality rates over the preceding five years 2016–2020) in the Keawsan subdistrict, Nabon district, Nakhon Si Thammarat province, Thailand, exceeded the thresholds set by the Thai Ministry of Public Health  [c − 1]); the selected difference between the two independent means (two groups)  design was used, comprising five steps: (1) preparation; (2) assessment; (3) development; (4) implementation; and (5) evaluation.https://nakhonsi.denguelim.com). A workshop was also planned and was aimed at allowing the same 59 key leaders to collect data on the larval indices surveillance and the dengue risk villages. Moreover, they were assigned their roles for participation in the model.The research team coordinated with the leader and committee of the Keawsan SAO in preparation for this study. The project plan meeting was set to be conducted with the SAO committee, which comprised 59 key leaders. Following the administrative management of the subdistrict, those available to participate comprised 10 community leaders, 20 VHVs, 2 public health providers from two primary care units, 2 from the direct public health office, 5 teachers from five schools in the subdistrict, 4 staff from four child development centers, 3 representatives from three temples, 10 members of the SAO council committee, and 3 SAO officials. The aim of the meeting was to describe the objectives of the project and brainstorm strategies to curb dengue and to provide the program timeline and the roles of all the stakeholders. It specifically aimed at preparing the data: for the computerized analytical procedures for supporting LISS; for predicting the dengue risk villages in the previous five years ; and for developing the computer program Houses’ Environment AssessmentThe environment of the houses in the 10 villages within the SAO’s area was assessed to set the solution plan and provide feedback data to the community. The survey format and items included participant characteristics, the environment of the houses, the water containers, and a larval index survey in eight types of containers which might be mosquito breeding sites ,20. Acco(2)UDS and ULISS AssessmentIn the six-step cognitive domain of Bloom’s revised taxonomy for learning, “understanding” consists of six cognitive levels: knowledge, understanding (comprehension), application, analysis, synthesis, and evaluation ,26. In t(1)Predicting High- and Low-Risk Dengue VillagesThe risk predictions were stratified as high-risk dengue village (H-RDV) or low-risk dengue village (L-RDV); to predict the risk of dengue in the two primary care units of the 10 villages of the subdistrict, we used a CPAR procedure, which was divided into the following three steps;Step 1. Determine the dengue risk using the dengue risk assessment criteria and the prediction of high/low risk criteria from the study in southern Thailand . Dengue The dengue severity aspect comprised three factors: (1) the endemic village factor, referring to the ongoing incidence of dengue cases; (2) the dengue herd immunity factor, which was demonstrable within the community and defined by the dengue morbidity rate of each village; and (3) the current morbidity rate factor, referring to the value comparing the current dengue morbidity rates with the median rates of the past five years. The dengue outbreak opportunity aspect comprised three factors: (1) the population movement, which refers to whether the area facilitates migration and allows for the virus to circulate in specific regions; (2) the population density in the village, which is self-explanatory and is an integral element considering that dengue spreads through mosquitoes ; and (3) the intensifying of the factors in villages for dengue prevention operations, including activities, projects, or interventions for dengue prevention in the villages. These interventions should be characterized as assessments of the dengue risk criteria, generally referring to the following five activities: the larval indices surveillance system, waste management, the larval indices level of the village, community capacity-related operations, and school-based dengue prevention operations. Together, the dengue severity aspect and the dengue outbreak opportunity aspect comprised 33 criteria, having a total score of 33 points.Step 2. A village-level evaluation of the risk areas that were under the responsibility of a primary care unit was conducted. For villages that had two primary care units, the evaluation was conducted according to the specified criteria established during a conference, wherein official representatives were tasked with solving the dengue-related problems on behalf of each primary care unit. Furthermore, the data on the illness rate, mortality rate, and total population of each village were comprehensively analyzed.Step 3. Villages with H-RDV and L-RDV were defined using half of the total scores . The risk cut-off value was set at 17 points. If a village scored 17 or more points, it was an H-RDV; if less than 17, an L-RDV, based on the two levels of risk that were confirmed in a previous study; this can be practically understood as high and low . (Supple(2)Setting Larval Indices Surveillance SystemThe larval indices surveillance system of the Keawsan SAO model applied the steps of the model . In tota(3)The UDS and ULISS Training ProgramThe program helped to predict the dengue risk villages and in the setting up of the larval indices surveillance system. The training programs focused on the dengue solution content and the larval indices surveillance system for the key stakeholders, including community leaders, village health volunteers (VHV), and student leaders.(4)Develop the Local Wisdom Innovation (LWI) with Herbs for Mosquito RepellantThe Keawsan SAO model team set up a plan for tackling dengue through interventions, such as predicting the risk of dengue in the 10 villages, implementing education programs for the stakeholders to better understand dengue and the larval indices surveillance system, and creating unique and innovative mosquito bite preventions. Based on budgetary support from the SAO, there were four steps for developing the local wisdom innovation of the 10 villages and 4 child development centers: (1) preparation with a workshop about producing the local wisdom innovation products; (2) The meeting conducted by the village leader group and the child development center; (3) the testing of the method for use; and (4) evaluation of the method for use in the community.We concluded that all the activities of the model were conducted for 12 weeks. The activities comprised the UDS and ULISS training programs and the designation of responsibilities for each stakeholder. This step was the evaluation of the process of development and the effects after using the Keawsan SAO dengue model. This step measured and compared the UDS and ULISS of the family leaders, VHVs, and student leaders before and after using the model. Moreover, it evaluated the larval indices level, the dengue morbidity rate, and the satisfaction of the stakeholders from the meetings of all the stakeholders.These self-reported questionnaires for UDS and ULISS comprised three parts and were applied to the VHVs. Part I included eight items on general characteristics such as sex, age, education level, experience, and duration of VHV role. Part II comprised 15 items that assessed the VHVs’ UDS. Part III assessed the ULISS and also consisted of 15 items. This survey took between 20 and 30 min to complete. The questionnaires for UDS and ULISS were administered as described in previous research . Three eThe UDS and ULISS of the family leaders and student leaders were assessed using the same questionnaires, modified to 10 UDS items and 10 ULISS items. Three experts assessed the CVIs, yielding values of 0.82 for the UDS items and 0.88 for the ULISS items, which verified their validity. Reliability testing resulted in Cronbach alpha coefficients for the UDS and ULISS of the 60 family leaders of 0.80 and 0.81, respectively, and for the 30 students, the Cronbach alpha coefficients for the UDS and ULISS were 0.72 and 0.73, respectively; these values showed acceptable reliability  of 0.70 or higher . These qBased on Bloom’s cut-off score of 80% ,29, we dThe questionnaire for measuring the project satisfaction was a short, six-item questionnaire that assessed opinions of overall satisfaction. Three experts reported CVI values of 0.92. The semi-structured questionnaires did not require reliability verification. The items were rated on a five-level scale of opinion: strong agreement, agreement, neutral, disagreement, and strong disagreement. At the evaluation step, the stakeholders met for discussion and reflection. The questionnaires for discussion by the community leaders and students were set based on unstructured questions. The participants reflected on aspects of the project, such as participation in the activities of the village, the larval indices surveillance system, the dengue training program, and the project’s utilities and barriers, and they made suggestions for solving dengue.https://nakhonsi.denguelime.com). The larval indices  were analyzed by the ratio, frequency, and percentage of the type of infestation found in the water containers. The data from the house environment survey, the six items that measured the stakeholders’ satisfaction and the participants’ characteristics were collected from the 134 VHVs and analyzed using descriptive statistics. The chi-square test and Fisher’s exact test were used to compare the scores for the UDS and ULISS of the VHVs, family leaders, and student leaders at the beginning point and the endpoint of the training program, and the results of the LISS were shown in the figures. The data that served to predict the risk of dengue in a village were analyzed using the entry assessment criteria, and the ULISS survey data were analyzed using a computer program  the model that was named the “Keawsan SAO dengue model”, which consisted of the six main activities, and (2) the outcomes of using the model. The six main activities of the Keawsan SAO dengue model were the setting of the team leader’s responsibility, the situation assessment, the prediction of the dengue risk villages, the larval indices surveillance system, the UDS and ULISS training program, and the local wisdom innovation.The preparation step showed that all the stakeholders in the Keawsan SAO dengue model had their responsibilities defined as the team leaders of the participation .(1)Houses’ Environment AssessmentThis section shows the assessment results for the 2372 housing environments and for the first larval indices surveillance system survey in June 2020. Of the respondents, 793 participants represented 793 households of the total houses . Most were women , aged between 36 and 59 years , followed by Buddhists , those who had a non-leader status in the community , and those who had higher elementary education . Most participants gave farmer as their main occupation ; approximately one-fifth had experienced dengue illness ; and slightly more than one-tenth had experienced dengue illness in the neighborhood . The average family income was THB 10,645 per month ; on average, the residents had resided in the community for 36.57 years (SD. = 19.6), had four family members, and received formal dengue training 0.34 times per year (SD. = 0.47). Most of the 719 houses were situated in a rural area (90.7%); 664 were a single house (83.7%); and 627 had a single story (79.1%). We observed that only 184 (23.2%) households had a tidy environment. Regarding water resources, usable water was piped to almost all of the 793 houses (88.5%); drinking water was supplied by water tanks to 679 households (85.6%); and 747 households had a toilet in the house (94.2%). The total numbers of water containers surrounding or within the houses were 3048 and 2684, respectively, and the average ratio was 3 to 4 containers per house. Moreover, there were 749 unused containers surrounding the houses.1 was responsible showed L-RDV, whereas the villages numbered 3, 4, and 8, which had PCU2 responsible of their health status, were H-RDV (The 10 villages were stratified into five H-RDVs (50%) and five L-RDVs (50%). The six villages  for which PCUre H-RDV .(1)In total, 2372 family leaders were surveyed using the larval indices and were helped in the elimination of the breeding sites of mosquitos in their houses and within the surrounding 100 meters of their houses every seven days.(2)The 134 VHVs and family leaders underwent surveys on the larval indices of 10 to 15 households, 5 schools, 4 child development centers, and 4 four temples. Their data were inserted in their “violet books”—notebooks for recording the results of the household larval data from the 10 to 15 houses surveyed per a VHV on 25th of each month—and the books were sent to the 30 zone leaders.(3)The 30 zone leaders collected the survey data from their VHVs, inserted them in their “blue books”, and sent the books to the community leader on the 28th of each month.(4)The 10 community leaders collected the data from each zone leader, inserted them in their “yellow books” on the 30th of each month, and sent those to the two primary care units.(5)http://nakhonsi.denguelim.com. The levels of the larval indices  were reported in a VHV meeting on the 9th of each next month. All the stakeholders were then used to construct a local wisdom innovation.Two primary care units gathered and entered the data from all villages into the website (6)The primary care units communicated the findings to all the stakeholders, to the SAO, and to the district public health official.The larval indices surveillance system is based on the following six steps: The six steps of the larval indices surveillance system were followed step-by-step, going from the households to the two primary care units and to the SAO .(1)The UDS and ULISS training programs were applied to 50 stakeholders in the community and the SAO. At the program’s onset, the UDS training was applied; the SAO devised the training for all the stakeholders regarding the objectives of the methods to tackle dengue, as well as the meaning, causes, signs, symptoms, and treatment for dengue illness. Thereafter, the ULISS training was applied, focusing on explaining the seven steps of the LISS and the roles of the stakeholders who participated in and supported the initiative.(2)The UDS and ULISS training programs were applied to all 134 participating VHVs; this is because the VHVs were the key stakeholders for tackling dengue in villages where the UDS and ULISS training programs were conducted. They underwent workshops for six months and completed the 15-item UDS and ULISS questionnaires pre- and post-training (in June and August 2020). After the village health volunteers’ training, they were requested to share their understanding of dengue solutions and the larval indices surveillance system with the family leader during the larval indices survey on every 25th day of each month from June to August 2020.(3)The UDS and ULISS training programs were also applied to 59 student leaders who represented five schools. They also completed the questionnaires before the test, in June 2020, and post-test, after training for 3 months.Aedes aegypti mosquito larvae, (3) herbal candles as a mosquito repellent, (4) herbal spray as a mosquito repellent, (5) a herbal scented bag as a mosquito repellent, (6) citronella essential oil for dengue elimination, (7) conducting community and household environment management and elimination of Aedes aegypti mosquito larvae, (8) red lime (Ca(OH)2) for reducing the Aedes aegypti mosquito larvae, (9) citronella as a mosquito repellent, and (10) volunteers to create a network for dengue prevention. According to the village dengue risk score and the context of the village, the VHVs, community leaders, child development centers, and family leaders were encouraged to create the local wisdom innovation in villages 1–10, such as (1) garbage-free communities, with three colored flags for community-based methods to avoid dengue and the aroma of citronella as a mosquito repellent, (2) placing reminder stickers for eradicating p < 0.05). These were conducted at the beginning of the project in the SAO. At the onset of the UDS and ULISS training programs, there were 109 VHVs; at the end, there were 90. There were no significant differences between before and after the implementation of the training programs, except for the duration of the training program of 12 weeks per year (p < 0.001), and one item (item number 12) was less significantly different (p < 0.01). Meanwhile, the scores for item 13 were not significantly different  had statistically significant differences (p < 0.001); meanwhile, a single item did not show a statistically significant increase for correct response ratios . Nonetheless, four personal characteristics showed significant differences (p < 0.05): having senior high school education (57.6%: 42.4%), dengue training time of more than twice per year (48.6%: 51.4%), no experience of dengue in the previous year (50.8%: 49.2%), and survey and elimination of larvae breeding sites every seven days (47.2%: 52.8%).The results of the comparison of the family leaders’ scores for the UDS before and after implementation showed an increase in good level score ratios and correct response ratios, which were statistically significant , those aged below 60 years (50.8%: 49.2%), and those living in the community for more than 10 years , aged 10 or older (91.5%), in junior elementary school (79.9%), completed larval indices surveys once a month (47.5%), had lived in the subdistrict area for more than 10 years (79.7%), had dengue training for more than one year (52.5%), and had no experience of dengue illness (76.3%). Only a few students had experienced dengue illness in their neighborhood (5.1%) or in their family (8.5%).p < 0.001; an item was statistically different if p < 0.01). The scores for item 5 were statistically significantly different (p < 0.05), and the scores for items 1, 2, and 4 showed no significant differences between the implementation periods . The larval indices of all 10 villages decreased after implementation. Thereafter, we analyzed the data that showed the effects post-implementation, such as the scores, the number of stakeholders, the larval indices before and after implementation, the names of the local wisdom innovations, and the larval indices , house index (HI), and container index (CI) before and after implementation are shown at  indices .The preparation, assessment, development, implementation, and evaluation of the Keawsan SAO dengue model took place during the last six months of 2020. According to the model, the prevention and control of dengue needs all the stakeholders in the subdistrict. Thereafter, the dengue morbidity rate in 2021  decreased compared with the data from the previous five years , aged between 35 and 59 years (65.4%); they received UDS and ULISS training from the VHVs (64.5%), engaged in activities for eliminating larvae in and out of their houses every seven days (77.4%), participated in the documenting activities of VHVs on the 25th of each month (67.1%), and participated in the local wisdom innovation of the village (54.3%) and in the school and the child development center (30.3%). The satisfaction levels of the participants in the Keawsan SAO dengue model were measured as part of the evaluation component of the community participatory action research. Almost all the stakeholders were highly satisfied: (1) the model decreased the dengue morbidity rate (85.0%); (2) the stakeholders had to participate in the dengue solution activities (87.6%); (3) the local wisdom innovation of the village could decrease dengue severity (84.2%); (4) the success of the model needed family leaders to eliminate mosquito larvae (89.4%); (5) the community needed to continue conducting projects to eliminate dengue (91.5%); and (6) the overall satisfaction of all the stakeholders was high (85.9%).In the final project meeting, 52 individuals represented the stakeholders, including SAO officials, teachers, VHVs, community leaders, and students. They discussed the solutions, processes, and effects of the program, which comprised all the activities mentioned above. Using thematic analysis, we summarized their reflections and extracted nine themes: (1) every person in the community must participate in the dengue solution initiatives; (2) members of the households must know and practice methods to tackle dengue; (3) villages should participate in dengue solution initiatives; (4) the VHVs must be responsible for and show the best ways to practice the methods to tackle dengue; (5) the community leaders must communicate and coordinate with other parties; (6) the SAO must participate in the initiatives and assign budgets; (7) the PCUs should serve as academic mentors; (8) the schools must be aware of the methods for curbing the spread of dengue; and (9) the Keawsan SAO dengue model must be strengthened by stakeholder empowerment. In this CPAR, we followed five steps to prepare, assess, develop, implement, and evaluate the effects of the Keawsan SAO dengue model, which was meant to provide a sustainable model for dengue prevention and control based on the SAO. We used the concepts of CPAR to evaluate the village dengue risk and the larval indices surveillance system; these methods concur with the methods proposed by previous research using the larval indices surveillance system within a district and the high- and low-dengue-risk primary care units . Howeverhttp://nakhonsi.denguelim.com) (accessed 8 October 2020), developed the guidelines for community participation, and developed and implemented training programs to build community capacity in the area [Based on the previous research, in the preparation step the stakeholders appointed a team leader for planning the projects, prepared data for the prediction of the dengue risk villages using a computer program  setting team leader responsibility, (2) situation assessment, 3) prediction of village dengue risk, (4) the six steps of the larval indices surveillance system, (5) the understanding of the dengue solution and the understanding of the larval indices surveillance system training program, and (6) local wisdom innovation with herbal mixtures as mosquito repellents. To ensure the transferring of knowledge to village residents, all stakeholders in the dengue prevention in the SAO  participated in the UDS and ULISS training programs. They are the key stakeholders in dengue prevention; this is similar to the previous community-based studies that placed importance on the participation process for dengue prevention and control  predicti,19,21. IThe ideas underlying our methods  are consistent with the concepts of integrated vector management advocated by the World Health Organization . MoreoveThese effects clearly show the results of the proposed intervention for controlling dengue, and they concur with the studies that evaluated the effectiveness of a community-based intervention for controlling dengue in Africa ,14. The http://nakhonsi.denguelim.com (accessed on 8 October 2020), and designing 14 local wisdom innovations. The evaluation of the effects before and after implementation showed an increase in scores for both the UDS and the ULISS questionnaires for the VHVs, family leaders, and students. Moreover, decreasing larval indices and dengue morbidity rates were related to the nine themes that were extracted from the discussions with community leaders and to the high levels of satisfaction among community members. However, the study might have been appropriate in Thailand but may prove inappropriate elsewhere. Therefore, the implementation of the prediction of H-RDVs and L-RDVs and the larval indices surveillance systems of the villages needs the support of the SAO’s budget or local organization and the participation of all stakeholders; the cohort study is warranted in the conducting and monitoring of activities for their long-term effects on sustainable dengue prevention and control in the future research.The Keawsan SAO dengue model is a local innovation that used a community- and SAO-based approach more frequently than simply enforcing local ordinances for tackling dengue; the proposed Keawsan SAO dengue model consisted of appointing community leaders, monitoring the situation of the dengue and housing environments, preparing data for predicting the village dengue risk and for establishing a surveillance system, and developing and implementing a UDS and ULISS training program for VHVs, family leaders, students, child development centers, and community leaders. It also included the setting up of the six steps of the LISS, creating the website


In order to develop a green environmental protection building material with low thermal conductivity and up to standard mechanical properties, in this study, pine waste wood chips were mixed into cement-based materials as fine aggregate, and three different kinds of cementitious binders were used, including sulfur aluminate cement (SAC), ordinary Portland cement (OPC), and granulated blast furnace slag (GBFS), to prepare a recycled light cementitious composite material. The mechanical, thermal conductivity, shrinkage, water absorption, and pore structure of a wood chip light cementitious composite material were studied by changing the Ch/B (the mass ratio of wood chip to binder). The results showed that the strength, dry density, and thermal conductivity of the specimens decreased significantly with the increase in the Ch/B, while the shrinkage, water absorption, and pore size increased with the increase in the Ch/B. By comparing three different kinds of cementitious binders, the dry density of the material prepared with OPC was 942 kg/m3, the compressive strength of the material prepared with SAC was 13.5 MPa, and the thermal conductivity of the material prepared with slag was the lowest at 0.15 W/m/K. From the perspective of low-cost and low-carbon emissions, it was determined that the best way to prepare a light cementitious composite with waste wood chips is to use granulated blast furnace slag (GBFS) as the cementitious binder.The CO With the development of the construction industry in recent years, the amount of concrete and wood has risen sharply, consuming resources while also producing a large amount of wood waste ,2. There2 emissions [2 emissions during cement production on global warming.According to statistics, cement production is resource intensive and accounts for roughly 7% of the world’s total COmissions ,4,5. Lowmissions  and woodmissions . Chowdhumissions  used theIn addition, the use of wood chips as an eco-aggregate to prepare lightweight concrete or mortar to reduce the weight of buildings while improving insulation performance is also becoming a growing topic of research . Dias etSome organic matter of the wood chips inhibits the compatibility of the substrate, resulting in an insufficient interfacial bonding between the substrate and wood chips, which in turn weakens the strength. Aiming to improve the interfacial bonding, the wood chips need to be pretreated; currently, the most common method is alkali treatment ,22,23. TA wood chip cement-based composite, as an innovative composite material, can also provide some additional functions, such as heat insulation and sound insulation, thus making up for its reduced mechanical energy to a certain extent ,28. MichThe previous literature on wood chip cementitious materials was reviewed, and the results showed that wood chips can replace part of the natural sand as a fine aggregate for the preparation of wood chip cementitious composites, which has important research significance. However, there are few studies on the preparation of lightweight wood chip cementitious composites by replacing 100% natural sand with wood chips; therefore, this experiment investigated the feasibility of preparing lightweight mortar from wood chips as a single fine aggregate without adding natural sand. This method is an innovative point of this experiment to further reduce natural sand mining. Without adding natural sand, lighter materials with a better thermal insulation effect can be obtained, which conform to the concepts of energy conservation and sustainable development.In this study, the aim was to develop a kind of lightweight wood chip cement-based material without natural sand. With cement as the control group, the feasibility of using alkali-excited blast furnace slag in wood chip cement-based material is discussed, so that it can achieve the effect of wood chip waste utilization and industrial solid waste. The mechanical properties, thermal conductivity, water absorption, dry density, shrinkage, and pore structure were comprehensively evaluated, and the effects of a cementitious binder type and the wood chip ratio on wood chip lightweight cementitious composites were analyzed to develop a green construction material with lower thermal conductivity and a high mechanical property.3 and that of ordinary Portland cement was 3.16 g/cm3. According to the national standard of GB/T18046-2017 [3 was used; its alkalinity coefficient was 0.94 and an activity coefficient of 41% was obtained in the test. The chemical and physical properties of these three cementitious materials are given in The cement used in this study was sulfur aluminate cement and ordinary Portland cement produced by Tangshan Polar Bear Cement Co., Ltd. , and Shanshui Cement Co., Ltd. , respectively. The density of the sulfur aluminate cement was 2.95 g/cm046-2017 , the gra3 and a size of 0.5–2 mm. The wood chips used in this study were pine waste wood chips with a density of 0.38 g/cmThe detailed mineral composition and element analysis of the wood chips are given in 3. The mass ratio of the water reducer was 0.5% of the cementitious material. The cementitious binder of the sulfur aluminate cement, ordinary Portland cement, and granulated blast furnace slag were marked groups A, B, C, respectively, and the detailed mix proportion is shown in With reference to the existing production process of cement-based plant fiber materials and the actual situation of the experiments ,34, on tThe alkaline exciter solution of group C was prepared from sodium hydroxide and sodium silicate solution, and the alkaline exciter solution with a modulus of 1 and a concentration of 3% on the mass percentage of binder was used in this test. The cementitious binder and the untreated wood chips were added together into the mortar mixing device and mixed at a low speed for 30 s. After, the water or alkaline exciter was added and mixed at a slow speed for 60 s. Then, the water reducing agent was added, and the mixing was continued at a high speed for 90 s. The mixture was mixed and loaded into the prepared test mold. To remove air bubbles from the fresh mix, all specimens were shaken with a shaker for 30 s. The samples were then covered with cling film to prevent moisture evaporation. After curing for 24 h, the specimens were demolded and placed under standard conditions of 20 ± 2 °C and 90 ± 5% relative humidity for further conditioning.In this study, testing for the mechanical properties, dry density, thermal conductivity, dry shrinkage, water absorption, and pore structure of the specimens was conducted to study the influences of the Ch/B ratio and the different binder types on the cementitious composites. Meanwhile, a SEM test was also conducted on the wood chip cement-based specimens to observe their microstructure.In order to clarify the basic mechanical properties of the wood chip-filled lightweight cementitious composites, the 40 × 40 × 160 mm specimens were prepared for mechanical property tests.According to the standard of JCJ/T 70-2009 , compresGenerally speaking, the testing for shrinkage of the mortar was for 7, 14, 21, 28, 56, and 90 days. Considering the specificity of the waste wood chips, the drying shrinkage was measured every 24 h for the first 7 days. The expression for the dry shrinkage rate is shown in Equation (1).The internal pore structure of the cementitious materials was analyzed generally by mercury piezometry , the gasThe effects of the incorporation of the pine wood chips and the type of cementitious binder on the compressive and flexural strength of the specimens were investigated. The results of the 28 d compressive strength and flexural strength of the different groups are shown in From From The dry density results of the specimens of each group are shown in The reason for the decline in the dry density was that with the increase in wood chips, the water requirement of the fresh mix increased, and the internal water was used for the hydration reaction and drying evaporation as the curing age increased. Therefore, the quality of the specimens constantly decreased. The higher the wood chip content, the more water is absorbed and lost by the specimen, and the greater the overall dry density of the specimen decreases. The dry density of the tested specimens was lower than that of ordinary mortar; thus, the wood chip lightweight cementitious material could be classified as lightweight mortar.Thermal conductivity is an important characteristics of the thermal insulation properties of a material. The thermal conductivity of each group is shown in The water absorption rate of each group of specimens was tested for 24 h, and the results are shown in The testing for the drying shrinkage strain of the mortar was carried out according to the national standard of JGJ/T70-2009. The drying shrinkage curves of the three groups of specimens are shown in It can be seen from x-axis characterize the internal pore area of the specimens, the transverse relaxation time was proportional to the pore diameter, and the change in the T2 spectrum can reflect the change in the internal pore structure of the specimen [The NMR technique was used to test the specimens with the size of 40 × 40 × 40 mm cured over 28 days. The transverse relaxation time T2 distribution of the specimens was obtained, as shown in From The study was conducted by comparing three binders, five kinds of Ch/B (wood-chip-to-binder-mass ratio), and the thermal conductivity and mechanical properties of the cement-based composites, and the following conclusions were obtained.(1)The strength, dry density, and thermal conductivity of the composites decreased with the increase in the Ch/B ratio, while the water absorption, pore size, and drying shrinkage of the composites increased with the increase in the Ch/B ratio.(2)The thermal conductivity of the cementitious composite material was lower between 0.24 and 0.15 W/m/K than that of conventional mortar. The addition of wood chips improved the thermal insulation properties of the material and reduced the dry density, and the water absorption rate showed an increasing trend.(3)The T2 spectrum characterized that the increase in the wood chip content led to an increase in the pores in the specimens, and the pores of the specimens in the sulfur aluminate cement and blast furnace slag groups are mostly small pores, while the pore size of the ordinary Portland group was relatively larger.(4)When the Ch/B was 1/10, the strength of the sulfur aluminate cement group and blast furnace slag group was 98% and 85% higher than the ordinary Portland cement group, respectively. The drying shrinkage of the blast furnace slag group was lower than 4% of that of the ordinary Portland group, and the production process of the blast furnace slag was energetic, waste friendly, and environmentally friendly, and the group had good mechanical properties and thermal insulation properties. Therefore, the best performance of the wood chip lightweight cement matrix composites prepared with alkali slag was considered as the best choice of binder.


In order to solve the problem of testing the water pressure resistance of lining structures of water-rich tunnels and the difficulty of implementing the existing model tests, a large-scale model test method was proposed relying on the New Yuanliangshan Tunnel threatened by high pressure and rich water. This method creatively transformed the external water pressure of the lining structure into internal water pressure, and the conversion coefficient of water resistance of lining under different sizes and loading modes was obtained by numerical calculation. Results showed that the ultimate water pressure resistance of the lining structure under an external uniformly distributed water pressure and local water pressure was 1.44 and 0.67 times of that obtained from the large-scale model tests, respectively. By conducting the large-scale model tests and combining with the conversion coefficient, the water pressure resistance of the actual tunnel lining could be obtained. Research indicated that water pressure resistance of K2.0 (bearing water pressure of 2.0 MPa) type lining at the transition section of karst caves and K3.0 (bearing water pressure of 3.0 MPa) type lining at the section of karst caves of the New Yuanliangshan Tunnel was 3.33 MPa and not less than 4.36 MPa, respectively, and the high reliability of the large-scale model tests was verified by numerical calculation, implying that the model test method could be extended to similar tunnel projects. China has a vast territory, and more than two-thirds of which are mountains and hills, especially in the western region. With the planning and rapid implementation of the traffic network in western China, the number of tunnels has also dramatically increased. However, water-rich geology is common in western China, and more and more tunnels that have been built, are under construction or under planning, will inevitably pass through water-rich areas. Under the action of high water pressure, tunnel lining may suffer from leakage, cracking, etc., and even engineering disasters such as water and mud inrush, which seriously threaten the safety of construction and operation of tunnels. Therefore, it is of great significance to study the ultimate water pressure resistance of tunnel lining structure to provide a reference for lining design and the construction of high-pressure and water-rich tunnels.Many scholars have carried out a series of related studies on the stress law of tunnel lining structure under water pressure, and achieved fruitful results. Wang et al.  studied In summary, the existing research on water pressure resistance of lining structures, including model tests and numerical simulation, were generally carried out by using the loading mode of external water pressure on the tunnel lining, applying water head on the outer boundary of the model or setting seepage boundary conditions to make the water pressure finally act on the outer surface of the tunnel lining. For the model test, the method of applying external water pressure on the outer surface of tunnel lining is more consistent with the actual water pressure acting on lining structure, but it is generally difficult to carry out. However, the large-scale model test carried out in this paper adopted the method of water pressure loading on the inner surface of the lining. Additionally, the numerical calculation method adopted in this paper was mainly to obtain the maximum water pressure resistance of lining structure by analyzing the failure process of tunnel lining under high water pressure, which was different from the focus of existing research.At present, the test and verification of the water pressure resistance of lining structures of high-pressure and water-rich tunnels is still very challenging, and the existing model tests using the loading mode of external water pressure are relatively difficult to implement. To solve this problem, relying on the New Yuanliangshan Tunnel project, a large-scale model test method for testing and verifying the ultimate water pressure resistance of lining structure of water-rich tunnel was designed and carried out in this paper, and the reliability of the model test method was verified by utilizing numerical calculation. The main organization of this paper is as follows: The concrete mixtures used in the large-scale model test include Portland cement, potable water, coarse aggregates, fine aggregates and admixture. The material properties of each mixture were shown in The New Yuanliangshan Tunnel has a total length of 11.077 km, which is constructed by fully utilizing the parallel pilot of the existing Yuanliangshan Tunnel for expanded excavation. The location map of the New Yuanliangshan Tunnel is shown in The waterproof capacity of primary lining is limited, but the construction of primary lining is essential to ensure construction safety. CF25 steel fiber shotcrete was used for the primary lining of the New Yuanliangshan Tunnel. The thickness of shotcrete was determined according to the level of surrounding rock and location. The thickness of shotcrete in the section of karst cave and transition section of karst cave was 20 cm. Φ22 and Φ25 combined hollow grouting anchor bars were adopted in the tunnel arch of surrounding rocks at all levels, and Φ22 and Φ32 mortar anchor bars were set in the side wall. The reinforcement mesh was made of HPB300 steel bar with a diameter of 6.5~12 mm. The small conduit was a kind of steel flower tube with a diameter of 42 mm and thickness of 3.5 mm. I16, I18, I20, I25b and H200 × 150 were adopted for the steel frame of primary lining.The construction quality of secondary lining structure can be basically guaranteed, so the leakage of tunnel lining is generally easy to occur at the construction joints of tunnel lining. The maximum design value of water pressure of lining structure of the New Yuanliangshan Tunnel under the extreme condition of water blocking and drainage restriction was up to 3.0 MPa, which put forward high requirements for design and construction of tunnel lining. For the high-pressure and water-rich area of the New Yuanliangshan Tunnel, karst is very developed. The surrounding rock at all levels in the transition section of the karst cave was provided with the circular reinforced concrete lining (K2.0 type) bearing water pressure of 2.0 MPa, with a lining thickness of 100 cm. The type II construction joint was selected as the circumferential construction joint, and the arrangement of waterstop was a combination of rubber waterstop and mid-buried steel plate waterstop. The cross section and circumferential construction joint of the lining structure in the transition section of the karst cave were shown in For the karst cave section in the high-pressure and water-rich area, the circular reinforced concrete lining (K3.0 type) capable of withstanding water pressure of 3.0 MPa was set, with a lining thickness of 120 cm. The type III construction joint was adopted as the circumferential construction joint, and the arrangement of waterstop was a combination of back stick rubber waterstop, mid-buried steel plate waterstop and mid-buried corrugated steel waterstop. The cross section and circumferential construction joint of lining structure in the section of the karst cave were shown in According to the distribution characteristics of tangential and radial stresses of ring or cylinder subjected to uniform internal and external pressure in the elasticity theory, we know that under the action of external uniform water pressure, the stress of radial and tangential is compressive stress. However, under the action of internal uniform pressure, the radial stress is compressive stress and the tangential stress is tensile stress. As we all know, the compressive strength of tunnel lining concrete is far greater than the tensile strength. Therefore, the tunnel lining is subject to tensile failure under the action of internal water pressure and compressive shear failure under the action of external water pressure. Actually, tunnel lining bears the effect of external water pressure, but it is difficult to carry out large-scale model test of water pressure resistance of tunnel lining by means of external water pressure loading. Therefore, from the point of view of the ultimate water pressure that tunnel lining can withstand when it is finally destroyed, a method of loading water pressure inside the model was proposed to transform the problem of tunnel lining bearing external water pressure into that of bearing internal water pressure for research in this paper, and the conversion relationship between the safety factor of water pressure resistance under the action of external water pressure and internal water pressure was established. According to the water pressure resistance of tunnel lining under internal water pressure obtained from indoor model test and the conversion coefficient obtained from numerical calculation, the water pressure resistance of lining under external water pressure can be obtained through reverse calculation.The inner diameter of lining structure of the New Yuanliangshan Tunnel was 8 m. In order to prepare the large-scale models, the inner diameter of the models was reduced to 0.4 m on the basis of ensuring that the thickness of the lining and the form of the construction joint were unchanged. The conversion relationship of safety factor between water pressure resistance of the test model and the lining was established by numerical calculation. Safety factor referred to the ratio of the actual water pressure resistance of tunnel lining to the design value of water pressure resistance. The higher the safety factor, the stronger the water pressure resistance of tunnel lining. The water pressure around the karst tunnel that deep buried was considered as the uniform water pressure and was replaced by a uniform load. Numerical calculation software of RFPA  was adopted to analyze the conversion relationship of safety factors of water pressure resistance of tunnel lining. RFPA is a numerical analysis software of material fracture process based on finite element stress analysis and statistical damage theory, which can simulate the whole process of the material from progressive failure to instability. There were four numerical calculation conditions in total, as shown in (1)Numerical calculation results under condition IThe size of numerical calculation model was 12 m × 12 m, with an internal radius of 4.17 m. The number of units was 400 × 400, with a unit size of 30 mm × 30 mm. The initial value of water pressure was 0 MPa, and the single step increment was 0.1 MPa. The numerical calculation models and results were shown in (2)Numerical calculation results under condition IIThe size of numerical calculation model was 12 m × 12 m, with an internal radius of 4.17 m. The number of units was 400 × 400, with a unit size of 30 mm × 30 mm. The initial value of water pressure was 0 MPa, and the single step increment was 0.1 MPa. The numerical calculation models and results were shown in (3)Numerical calculation results under condition IIIThe size of numerical calculation model was 12 m × 12 m, with an internal radius of 4.17 m. The number of units was 400 × 400, with a unit size of 30 mm × 30 mm. The initial value of water pressure was 0 MPa, and the single step increment was 0.1 MPa. The numerical calculation models and results were shown in (4)Numerical calculation results under condition IVThe size of numerical calculation model was 3 m × 3 m, with an internal radius of 0.2 m. The number of units was 300 × 300, with a unit size of 10 mm × 10 mm. The initial value of water pressure was 0 MPa, and the single step increment was 0.1 MPa. The numerical calculation models and results were shown in (5)Analysis of numerical calculation resultsThe calculation results of safety factor of water pressure resistance were shown in It can be seen from In order to test the water pressure resistance of the lining structure (K2.0 type) in the transition section of karst cave and the lining structure (K3.0 type) in the section of karst cave, two test models under two different conditions were prepared, respectively, and their use conditions and waterstop settings were shown in The pressure pump station was used to pressurize the system, which was composed of a power system, a distribution system and a working system. The power system was mainly composed of a motor and a pressure pump, which converted mechanical energy into pressure energy. The distribution system was mainly used to regulate the direction, speed and pressure of the liquid. The distribution system in this test was mainly utilized to regulate the pressure through the overflow valve. The working system mainly connected the liquid outlet to the test specimen, pressurized the test specimen, and converted the pressure energy into osmotic force. The working principal diagram of the pressure pump station and the pressure pump are shown in RFPA numerical calculation software was utilized to study the water pressure resistance of tunnel lining. The water pressure resistance of the lining (K2.0) in the transition section of karst cave and the lining (K3.0) in the section of karst cave of the New Yuanliangshan Tunnel were calculated and analyzed, and the results were compared with the large-scale model tests, so as to verify the reliability and accuracy of the model tests. It should be noted that the surrounding rock within 5 m around the karst cave with high water pressure was reinforced by grouting during the construction of the New Yuanliangshan Tunnel, so the influence of grouting stones was considered in the numerical calculation.3, so the uniform stress (p) on the upper boundary of the model was 10 MPa. Coefficient of lateral pressure (λ) was set to 1.5. Homogeneity of model (M) represented the homogeneity of material. The larger the value of M, the more homogeneous the macroscopic properties of material. Considering that the size of the smallest unit of the numerical calculation model was 25 cm, M could be set to 80. Since the compressive strength of rock is far greater than its tensile strength, the modified Mohr-Coulomb criterion considering tensile truncation was adopted as the strength criterion of unit failure.In order to weaken the influence of boundary effect, the numerical model was taken as three times the tunnel diameter. The size of calculation model was 100 m × 100 m, and the tunnel inner diameter was 10 m. The thickness of grouting stone body was set as 5 m, and the thickness of primary lining was 0.2 m. In addition, the thickness of the secondary linings were 1.0 m and 1.2 m, respectively. Numerical calculation conditions were shown in The rock and soil mass of the stratum of the karst cave section where the New Yuanliangshan Tunnel passed through was mainly limestone, and the filling material in the karst cave of the grouting stratum was mainly silty fine sand. According to the geological survey report and the test results of on-site borehole sampling, the physical and mechanical parameters of surrounding rock and grouting stone in the numerical calculation model were finally determined as shown in The primary lining of the tunnel was composed of reinforcement mesh + CF25 steel fiber shotcrete with a thickness of 20 cm + H200 steel frame, with a longitudinal interval of 50 cm. C30 concrete was adopted for the secondary lining. Numerical calculation parameters of support structure were shown in The test process of water pressure resistance of the K2.0 type lining in the transition section of karst cave of the New Yuanliangshan Tunnel was shown in The test process of water pressure resistance of the K3.0 type lining in the section of karst cave of the New Yuanliangshan Tunnel was shown in The water pressure resistance of K2.0 and K3.0 type linings was studied by numerical simulation, the results of which were shown in To sum up, the results of model test and numerical calculation were shown in Through comparative analysis of (1)For solving the problem of testing and verifying the water pressure resistance of lining structures of water-rich tunnels and the difficulty of implementing the existing model tests, the large-scale model test method that converted external water pressure of tunnel lining to internal water pressure for analyzing water pressure resistance of lining structures was creatively proposed. By utilizing this method, we verified that the lining structures of the New Yuanliangshan Tunnel crossing high-pressure and water-rich karst caves meet the design requirements of resisting water pressure of 3.0 MPa.(2)The ultimate water pressure resistance of tunnel lining structure under external uniform water pressure and external local water pressure was 1.44 times and 0.67 times of that obtained from the large-scale model tests, respectively. The results of large-scale model tests indicated that the water pressure resistance of the K2.0 type lining in the transition section of karst cave and the K3.0 type lining in the section of karst cave of the New Yuanliangshan Tunnel was 3.33 MPa and no less than 4.36 MPa, respectively. Additionally, the accuracy of the large-scale model tests was verified by numerical calculation.(3)The large-scale model test method for testing and verifying water pressure resistance of tunnel lining structure provided a new idea and reference for the research on water pressure resistance of tunnel lining. In addition, the model test method reduced the difficulty of testing the water pressure resistance of tunnel lining, and the numerical calculation verified its high reliability and accuracy, which could be extended to similar tunnel projects and other types of tunnel lining under the action of water pressure to study the water pressure resistance of lining structures.The large-scale model test research on water pressure resistance of lining structure of high-pressure and water-rich tunnel was carried out in this paper, and the reliability of the model test was verified by using numerical calculation method. The main conclusions were as follows:


To characterize the type of toxicity of ternary mixtures of nanoparticles, we successfully tested a previously developed approach for assessing the combined toxicity of metal ions. In this approach, the effects are classified by a null, positive, or negative change in the toxicity of binary nanoparticle mixtures when modeled against the toxicity of the third agent added.Our studies of exposure to binary mixtures of nanoparticles (TiO In 2015, we ) was eitAs for ternary mixtures of toxicants in full dose, we proposed a novel approach to characterizing their effects based on the consideration whether addition of a third agent to the mixture of the other two led to a negative (Class A), positive (Class B), or no change (Class C) in response. We revealed some stable patterns in this classification that reproduced fully or partly when Mn, Ni, or Cr were added one by one as a third component to the combination. Thus, for the absolute majority of health effects, the classification proved to be inherently consistent.We maintained that the relevance of the proposed classification to health risk analysis and management was as follows. When assessing the total health risk from exposure to three toxicants using the conventional approach based on summation of single risks, it is essential to take into account the probability of under- or overestimation of the result depending on the classification of the effect. Most deleterious Class A effects are more important in terms of the precautionary paradigm, while the effects of Classes B and C, denoting positive and null changes, respectively, may be considered as providing an additional margin of safety rather than justifying less conservative risk management scenarios.Besides, we found a complicated reciprocal influence of combined metals on their retention in the kidneys, liver, spleen, and brain, which might presumably be one of the possible mechanisms of combined toxicity, but not always the most important one.Later on, we tested a similar approach for assessing the combined toxicity of metals as nanoparticles.The master alloy production process is associated occupationally with workspace air pollution by a combination of metal oxide nanoparticles (MeO NPs) arising as by-products of the technology. In multicomponent chemical pollution settings, there are typically two or three air pollutants observed in the highest concentrations and/or posing a major hazard that are given priority. A review of industrial air quality monitoring data showed that the priority air contaminants for the production of master alloys are aluminum, titanium, and silicon, the health effects of which have been described in numerous studies ,9,10,11.2O3, SiO2 and TiO2) exposure group of rats were significantly different from those in control animals.As can be seen from 2О3 + SiO2 + ТiO2 exposure group was significantly different from the control, ceased to be so different in response to dose reduction, as follows: brain weight decrease and reduced glutathione in blood hemolysate. Further to the above, we can highlight the normalization of several indices in which the shift caused by the combination under consideration in full dose was statistically insignificant but quite obvious, as follows: a decrease in blood serum lactate dehydrogenase and urea, urinary coproporphyrin, and 24-h urine volume.The experiment also included a group of rats administered half doses of the MeO NP species, mainly for the construction of a mathematical model of combined toxicity using the response surface method. To avoid complicating the table further, we did not include data for this group and just specified that only two out of the seven indices, in which the Al2О3 + SiO2 + ТiO2 nanoparticle exposure.Thus, the toxic effect of the ternary combination assessed by shifts in the functional and biochemical indices of the rat organism appeared to be minor, and, moreover, it did not demonstrate any explicit dose dependence. Neither were there any statistically significant differences from the same indices of the three binary exposure groups. A two-stage analysis gave a clearer picture of the combined 3-factor toxicity. 2O3 as the third factor, while for the other two MeO NPs, it was Class C that prevailed (44%).In general, out of the toxic effects in At the same time, there are cases noted in modeling the impact of this ternary combination where an effect could not be ambiguously referred to one of the following three classes: in some parts of the range of combined doses, the change of the binary toxicity type in the presence of a third agent may be regarded as more detrimental (Class A), while in others as less detrimental (Class C) to health. A typical example of this kind is illustrated by the isobolograms in 2O3 + TiO2 on alkaline phosphatase activity in blood serum in the absence of the third agent was additive over the entire range of doses with a certain tendency towards antagonism, whereas in the presence of SiO2 NPs, this type of Al2O3 + TiO2 combined toxicity persisted only at the lowest doses of these nanoparticle species (Class C). At the same time, combinations of high doses of any of them with low doses of the other demonstrated different variants of opposite action (Class B), while combinations of high doses of both factors acted unidirectionally in synergism (Class A).In this case, the effect of AlIn such complicated cases, it is unlikely to be possible to formalize the determination of the prevailing class of 3-factor combined toxicity, and the choice should be based on expert judgement, taking into account various toxicological and hygienic considerations, but generally proceeding from the precautionary principle. In the above case, for instance, the change of any type of binary toxicity to synergism in some parts of the dose range should prevail in the latter, i.e., predetermine its classification into Class A.2 to the most nephrotoxic combination of Al2O3 + TiO2 enhanced the effect slightly (possible antagonism), while Al2O3 added to the combination of SiO2 + TiO2 doubled it to a statistically significant level, though for brush border loss only. Thus, as in the above analysis of functional and biochemical effects, Al2O3 NPs again seem to play a leading role (even at a relatively low dose) in the combined toxicity of MeO NPs, though in relation to an isolated impact on the kidneys. The association of this effect with exposure to the combination under study is, in itself, confirmed by its obvious dependence on the effective dose of the entire combination.2O3 = 0.36, TiO2 = 2.12, and SiO2 = 0.75), the combined action of these factors raises this index to 5.70, which points to a possible synergism. Similar summation of the values for the second effect of nephrotoxicity  gives an expected value of 0.87  for the sum of three isolated effects and 1.04 for the actual combined effect, also suggesting some synergism.As rough mathematical estimates show, whereas the sum of increases in brush border loss over the three agents compared to the control value is equal to 3.23 , as shown in Comparison of the binary and ternary exposure groups  gives an2O3 was considered as the third component of the combination . The genotoxic effects of the three binary combinations were higher  than the effects of the individual agents in them taken separately, the presence of Al2О3 in the combination being of greatest importance here as well. Considering again the difference between DNA fragmentation factors for the experimental and control groups as a measure of the genotoxic effect, gives an impression of synergism in this effect of the ternary combination as well as in the effect of binary combinations containing Al2О3 . However, in this case as well, the type of combined effect we deal with can only be established in general form based on the results of RSM modeling and the proposed classification.The association between this effect and toxic exposure is again evidenced by the dependence of the first on the dose of the second. Indeed, whereas the ternary combination of the nanoparticle species in full dose increased the fragmentation factor 1.6 times against the control value, the combination of half doses increased it 1.2 times only (2O3 is considered as a background (third) component, the obvious antagonism in the effect of the other two turns into additivity with a tendency towards synergism, i.e., the type of combined action that is more harmful for the organism (Class A). However, if the third component is TiO2, then the genotoxicity of SiO2 + Al2O3, which was strictly additive in its absence, approximates a single-factor effect, determined mainly by the dose of Al2O3, which is less unfavourable (Class B). Finally, SiO2 added to ТiO2 + Al2O3 did not change the super-additive type of action of the latter (Class C). Thus, as in the case of functional and biochemical indices of combined toxicity, the classification of the three-factor genotoxicity of Al2O3 + TiO2 + SiO2 NPs appears to be ambiguous, depending on which of these factors is considered as the third one. The precautionary principle, which is crucial with respect to genotoxic effects, suggests that it would be correct to refer this ternary combination to the most unfavorable Class A, and so much more so that the latter is determined by the factor of Al2O3, which both by itself and in binary combinations, proved to be the most hazardous.As the isoboles in ® CrossBeam® Workstation . Airborne particles were sampled on polycarbonate filters in the workspace of the aluminum titanium master alloy smelting shop at VSMPO-AVISMA Corporation, Verkhnyaya Salda, Sverdlovsk Region, Russia, and analyzed for elemental composition by SEM-energy-dispersive spectroscopy using the Carl Zeiss AURIGA2, SiO2, and Al2O3 nanoparticles were specially prepared for the experiment by laser ablation of the surface of a superpurity metal plate under a layer of deionized water. The particles had spherical or near-spherical shape (see 2O3 particles as an example) and a symmetrical size distribution ”. As only morphometrically assessed responses of kidneys proved dependent on such dose decrease, we have not included functional responses of this additional group in Subchronic exposure to metal oxide nanoparticles (MeO NPs) was modelled by repeated intraperitoneal injections of corresponding suspensions into four-month-old outbred rats of our own breeding with an initial body mass of 250–350 g. Six groups of 12 male rats each were exposed thrice a week for six weeks. A single dose of SiOThe animals were kept in a specially organized compartment of the vivarium in compliance with the International Guiding Principles for Biomedical Research Involving Animals developed by the Council for International Organizations of Medical Sciences, and the International Council for Laboratory Animal Science (2012). The experiment was approved by the Local Bioethics Committee of the Yekaterinburg Medical Research Center for Prophylaxis and Health Protection in Industrial Workers, Yekaterinburg, Russia.More than 50 physiological, cytological, and biochemical indices of control and experimental animals were assessed following the six-week exposure period, during which the health status of the rats was monitored regularly and seven body weight measurements were taken, the last one immediately preceding euthanasia.To study the function of the central nervous system, we applied the summation threshold index most frequently used in experimental toxicology . The higThe rats were quickly sacrificed by decapitation under raush narcosis and their blood was collected to analyse hTmoglobin, red blood cell count, the proportion of reticulocytes, white blood cell count, and succinate dehydrogenase (SDH)|activity in blood lymphocytes. The levels of hTmoglobin and red blood cell count were measured using a Mythic 18 analyzer with appropriate diagnostic kits; the white blood cell count was performed on stained blood smears. SDH activity was assessed cytochemically using paranitroviolet tetrazolium and expressed as the number of formazan granules in 50 cells .An important additional functional indicator of erythropoiesis is an elevated count of reticulocytes, which are immature red blood cells developing after the loss of nuclei by normoblasts. A characteristic feature of reticulocytes is the presence of cytoplasmic granular and filamentous substances in their cytoplasm detected by supravital staining  with brilliant cresyl blue. The number of reticulocytes was counted per 1000 erythrocytes .The liver function was assessed by the indices of total protein, albumin to globulin ratio, and alanine aminotransferase and aspartate aminotransferase activity .Coproporphyrin and delta-aminolevulinic acid levels in urine were used to estimate porphyrin metabolism .We also measured the serum malondialdehyde and catalase content to assess lipid peroxidation and antioxidant mechanisms in the organism .Along with the above techniques, we evaluated the genotoxicity of this combination of substances. One of the most commonly used methods of genotoxicity assessment is the amplified fragment length polymorphism assay. It allows detecting DNA fragmentation, i.e., estimating quantitatively the degree of genotoxicity of damaging agents used. The leukocyte fraction is isolated from the obtained whole blood samples using one-step ficoll-verografin density gradient separation. The samples are then grouped in accordance with the results. DNA is isolated by acid phenol-chloroform extraction. The polymerase chain reaction is carried out in LaMMT modification increasing the PCR sensitivity by 8–10 times. To run the reaction, use is made of specific tritium-labelled primers and nucleotides . The resulting PCR amplification product is separated by horizontal agarose gel electrophoresis in TAE buffer at 100 V for 15 min.Following the electrophoresis, the gel plates are divided into tracks, each of which is cut into 5-mm-long sections. The resulting gel fragments are placed in vials containing 3.0 mL of absolute isopropanol. The vials are heated to 80 °С for two hours. After extraction of the labelled amplified fragments from the gel, 6.0 mL of a simple toluene scintillator is added to the vials followed by liquid scintillation counting using an automated Beta-2 counter. The ratio of radioactive activity in the “tail” and “head” of the preparation is a quantitative measure of DNA fragmentation .t-test in Microsoft Excel. These differences were considered statistically significant if the probability of a random difference did not exceed 5% (p < 0.05).Differences between the group averages were processed using the Student’s 2 + SiO2, TiO2 + Al2O3, or SiO2 + Al2O3) in the absence or presence of a third one. At this stage, the response of a certain index to the combined (binary) exposure was mathematically described using isobolograms constructed from the following regression model:The first stage of the analysis involved classification of all quantitative indices of the toxic effects under study by type of combined toxicity of each combination of two factors  is the analytical model of the response surface. The virtual “sectioning” of this surface on different levels corresponding to different values of the outcome Y or of the doses x, provides a family of Loewe isoboles that may have the same or a different form and/or different slopes, and thus render the interpretation of binary combined toxicity types both easy and illustrative.No statistically significant effect of both toxicants taken together or separately was observed initially in the absence of the third agent but an adverse effect was revealed following the addition of the latter;The initial situation was characterized by antagonism under a unidirectional effect of the toxicants while the final state was characterized by homogeneous additivity and even synergism (in at least one range of doses and/or levels of response);The initial situation was characterized by homogeneous additivity under a unidirectional effect of the agents while the endpoint was characterized by synergism (in at least one range of doses and/or levels of response).As a principle of toxicological characterization of a ternary mixture of toxicants, we applied the classification of changes from one type of combined effect produced by two toxicants to another following the addition of a third agent, meaning (A) deterioration, (B) improvement, or (C) no change. In accordance with this classification, Class A, representing a negative change, includes indices undergoing one of the following transitions:From any type to the type of no effect of each of the toxicants along and in combination;From synergism (detected in at least one range of doses and/or levels of response) to uniform additivity and, even more so, to antagonism in at least one range of doses and/or levels of response under the unidirectional effect of the toxicants;From uniform additivity to subadditivity of a unidirectional effect or counter-directional effect in at least one range of doses and/or response levels.Similarly, Class B that shows a positive change following the addition of the third agent describes the following opposite transitions:Finally, Class C represents no change from one type of combined toxicity to another, as well as changes that do not modify the overall qualitative picture of the combined effect .To assess the combined effect of metal oxide nanoparticles, we applied the classification of combined three-factor toxicity based on a two-stage approach, enabling changes in the type of binary toxicity following the addition of a third agent to be identified. This assessment was performed by mathematical modeling of combined toxicity types, which showed that the outcomes of exposure to a ternary mixture can be more or less noxious  or remain unchanged (Class C) following the addition of a third component. When assessing the cumulative health risk from exposure to a ternary mixture of toxicants based on the generally accepted approach of single factor risk summation, it is essential to take into consideration that the result of such an assessment may be either underestimated  or somewhat overestimated . The first option is more important from the perspective of the precautionary principle, while the second one should be considered only as an additional margin of safety.