Keeping in view the importance of new defined and well growing spherical fuzzy sets, in this study, we proposed a novel method to handle the spherical fuzzy multi-criteria group decision-making (MCGDM) problems. Firstly, we presented some novel logarithmic operations of spherical fuzzy sets (SFSs). Then, we proposed series of novel logarithmic operators, namely spherical fuzzy weighted average operators and spherical fuzzy weighted geometric operators. We proposed the spherical fuzzy entropy to find the unknown weights information of the criteria. We study some of its desirable properties such as idempotency, boundary and monotonicity in detail. Finally, the detailed steps for the spherical fuzzy decision-making problems were developed, and a practical case was given to check the created approach and to illustrate its validity and superiority. Besides this, a systematic comparison analysis with other existent methods is conducted to reveal the advantages of our proposed method. Results indicate that the proposed method is suitable and effective for the decision process to evaluate their best alternative. The complication of a system is growing every day in real life and getting the finest option from the set of possible ones is difficult for the decision makers. To attain a single objective is difficult to summarize but not incredible. Many organizations found difficulties with setting motivations, goals and opinions’ complications. Thus, organizational decisions simultaneously include numerous objectives, whether they regard individuals or committees. This reflection suggests, according to criteria solved optionally, restricting each decision maker to attain an ideal solution-optimum under each criterion involved in practical problems. Consequently, the decision maker is more concentrated to establish more applicable and reliable techniques to find the best options.To handle the ambiguity and uncertainty data in decision-making problems, the classical or crisp methods cannot be always effective. Thus, dealing with such uncertain situations, Zadeh  in 1965 After many applications of fuzzy set theory, Atanassov observed that there are many shortcomings in this theory and introduced the notion of intuitionistic fuzzy sets  to generIFS theory and PyFS theory have been successfully applied in different areas, but there are situations that cannot be represented by it in real life, such as voting, we may face human opinions involving more answers of the type: yes, abstain, no and refusal  happened in reality and IFS and PyFS could not handle it). Thus, Cuong  proposedThe neutrosophic set is another important generalizations of the classic set, fuzzy set, intuitionistic fuzzy set and picture fuzzy set to deal with uncertainties in decision-making problems. Many authors contributed in the decision-making theory using neutrosophic information. Ashraf  proposedThe picture fuzzy set becomes more famous by introducing various kinds of aggregation operators. However, it has a shortcoming in that it is only valid for the environment whose sum of degrees is less than or equal to one. However, in day-to-day life, there are many situations where this condition is ruled out. For instance, if a person giving their preference in the form of positive, neutral and negative membership degrees towards a particular object is 0.7, 0.3 and 0.5, then clearly this situation is not handling with picture fuzzy set. In order to resolve it, Ashraf  proposed. Ashraf  proposed. Ashraf  proposed. Ashraf ,44,45.The logarithmic operations being good alternatives, compared with the algebraic operations, have the potential to offer similar smooth estimations as the algebraic operations. However, there is little investigation on logarithmic operations on the IFSs and PyFSs. Motivated by these ideas, we develop a spherical fuzzy MCDM method based on the logarithmic aggregation operators, with the logarithmic operations of the spherical fuzzy sets (SFSs) handling spherical fuzzy MCDM within SFSs.We develop some novel logarithmic operations for spherical fuzzy sets, which can overcome the weaknesses of algebraic operations and capture the relationship between various SFSs.We extend logarithmic operators to logarithmic spherical fuzzy operators, namely logarithmic spherical fuzzy weighted averaging (L-SFWA), logarithmic spherical fuzzy ordered weighted averaging (L-SFOWA), logarithmic spherical fuzzy hybrid weighted averaging (L-SFHWA), logarithmic spherical fuzzy weighted geometric (L-SFWG), logarithmic spherical fuzzy ordered weighted geometric (L-SFOWG) and logarithmic spherical fuzzy hybrid weighted geometric (L-SFHWG) to SFSs, which can overcome the algebraic operators’ drawbacks.We develop the spherical fuzzy entropy for spherical fuzzy information, which can help to find the unknown weights information of the criteria.We develop an algorithm to deal with multi-attribute decision-making problems using spherical fuzzy information.To show the effectiveness and reliability of the proposed spherical fuzzy logarithmic aggregation operators, the application of the proposed operator in emerging technology enterprises is developed.Results indicate that the proposed technique is more effective and gives more accurate output as compared to existing studies.Thus, the goal of this article is to propose the decision-making method for MCDM problems in which there exist the interrelationships among the criteria. The contributions of this study are:In order to attain the research goal that has been stated above, the organization of this article is offered as: The concepts and basic operations of existing extensions of fuzzy sets are recalled in this section, and they are the foundation of this study.Definition 1.A mapping .A mapp(1) (2) where Definition 2.A mapping .A mapp(1) (2) where As different norms are the curial elements for proposing aggregation operators in fuzzy set theory, here we enlist some basic norms operations for fuzzy sets in Now, we enlist different types of norms with its generators too in Definition 3.For a set ℜ, by a Pythagorean fuzzy set in ℜ, we mean a structurein which .For a Definition 4.For a set ℜ, by a picture fuzzy set in ℜ, we mean a structurein which .For a Definition 5.For a set ℜ, by a spherical fuzzy set in ℜ, we mean a structurein which .For a Ashraf and Abdullah  proposedDefinition 6.For any two SFNs, (1) (2) (3) (4) (5) Definition 7.For any two SFNs, (1) (2) (3) (4) (5) Ashraf and Abdullah  introducDefinition 8.For any three SFNs, (1) (2) (3) (4) (5) (6) (7) (8) Definition 9.For any SFN, (1) (2) The score and accuracy values defined above suggest which SFN is greater than other SFNs. The comparison technique is defined in the next definition.Definition 10.For any SFNs, (1) If (2) If (3) If (a) (b) (c) Ashraf and Abdullah  proposedDefinition 11.For any collection of SFNs, where Definition 12.For any collection of SFNs, where Definition 13.For any collection of SFNs, where Definition 14.For any collection of SFNs, where Definition 15.For any collection of SFNs, where Definition 16.For any collection of SFNs, where Basically, we familiarize the concept of entropy, when probability measures the discrimination of criteria being imposed on multi-attribute decision-making problems. Non-probabilistic entropy firstly approximated by De Luca and Termini  also preDefinition 17.Let .Let δηDefinition 18.Let F be any fuzzy set in ℜ, fuzzy entropy for the set F, we mean a structure.Let F Definition 19.Let F be any fuzzy set in ℜ, and, for Pythagorean fuzzy entropy for the set F, we mean a structure.Let F Definition 20.Let F be any fuzzy set in ℜ, spherical fuzzy entropy for the set F, and we mean a structureMotivated by the novel concept of spherical fuzzy set, we introduced some novel logarithmic operational laws for SFNs. As real number system Definition 21.For any SFN, in which the neutral grade isand the negative grade isTherefore,is SPN.Definition 22.For any SFN, then the function Theorem 1.For any SFN, Proof. ℜ, which means that ℜ, Since any SFN Case-1 When Case-2 When Example 1.Suppose that, for any SFN, In addition, if Now, we give some discussion on the basic properties of the L-SFN.Theorem 2.For any SFN, (1) (2) Proof. (1) According to Definitions 7 and 22, we obtain(2) According to Definition 22, we obtainDefinition 23.For any two L-SFNs, (1) (2) (3) (4) Theorem 3.For any two L-SFNs, (1) (2)Proof. This is straightforward from Definition 23, so the procedure is eliminated here. □Theorem 4.For any two L-SFNs, (1) (2)Proof. This is straightforward from Definition 23, so the procedure is eliminated here. □Theorem 5.For any two L-SFNs, (1) (2) (3) (4) (5) Proof. (1) Since, from Definition 23, we have(2) Since, from Definition 23, we have(3) and (4) are similarly as above, so the procedure is eliminated here.(5) Since, from Definition 23, we haveDefinition 24.For any L-SFN, (1) (2) The score and accuracy values defined above suggest which L-SFN is greater than other L-SFNs. The comparison technique is defined in the next definition.Definition 25.For any L-SFN, (1) If (2) If (3) If (a) (b) (c) Now, we propose novel spherical fuzzy logarithmic aggregation operators for L-SFNs based on defined spherical fuzzy logarithmic operations laws as follows:Definition 26.For any collection of SFNs, where Theorem 6.For any collection of SFNs, where Proof. Using mathematical induction to prove Theorem 6, we therefore proceed as follows:(a) For Then,(b) Now, Theorem 6 is true for (c) Now, we prove that Theorem 6 for n. Therefore,Thus, Theorem 6 is true for Remark 1.If Properties: The ℜ. Then, if the collection of SFNs (1) Idempotency: For any collection of SFNs, ℜ. ℜ, therefore(2) Boundedness: For any collection of SFNs, ℜ.If (3) Monotonically: For any collection of SFNs, Definition 27.For any collection of SFNs, where Theorem 7.For any collection of SFNs, where Proof. The proof is similar to Theorem 6. Thus, the procedure is eliminated here. □Remark 2.If Properties: The ℜ.Then, if a collection of SFNs (1) Idempotency: For any collection of SFNs, ℜ. ℜ; therefore,(2) Boundedness: For any collection of SFNs, ℜ. If (3) Monotonically: For any collection of SFNs, Definition 28.For any collection of SFNs, where Theorem 8.For any collection of SFNs, where Proof. This proof issimilar to Theorem 6, so the procedure is eliminated here. □Remark 3.If Properties: The ℜ. Then, if a collection of SFNs (1) Idempotency: For any collection of SFNs, ℜ. ℜ; therefore,(2) Boundedness: For any collection of SFNs, ℜ.If (3) Monotonically: For any collection of SFNs, Definition 29.For any collection of SFNs, where Theorem 9.For any collection of SFNs, where Proof. Using mathematical induction to prove Theorem 9, we proceed as follows:(a) For (b) Now, Theorem 9 is true for (c) Now, we prove that Theorem 9 for n. Therefore,Thus, Theorem 9 is true for Remark 4.If Properties: The ℜ.Then, if a collection of SFNs (1) Idempotency: For any collection of SFNs, ℜ. ℜ, therefore(2) Boundedness: For any collection of SFNs, ℜ.If (3) Monotonically: For any collection of SFNs, Definition 30.For any collection of SFNs, where Theorem 10.For any collection of SFNs, where Proof. This proof is similar to Theorem 9, so the procedure is eliminated here.□Remark 5.If Properties: The ℜ.Then, if the collection of SFNs (1) Idempotency: For any collection of SFNs, ℜ. ℜ, therefore(2) Boundedness: For any collection of SFNs, ℜ. If (3) Monotonically: For any collection of SFNs, Definition 31.For any collection of SFNs, where Theorem 11.For any collection of SFNs, where Proof. This proof is similar to Theorem 9. Thus, the procedure is eliminated here. □Remark 6.If Properties: The ℜ. Then, if collection of SFNs (1) Idempotency: For any collection of SFNs, ℜ. ℜ, therefore(2) Boundedness: For any collection of SFNs, ℜ. If (3) Monotonically: For any collection of SFNs, Step 1:m probable alternatives and n criteria, where t experts, where kth expert. The expert Let When we construct the spherical fuzzy decision-making matrices, Taking the decision information from the given matrix Step 2:In this step, we find the collective spherical information using a spherical fuzzy weighted averaging aggregation operator.Step 3:In this step, we find the weights of each of the criteria by using the spherical fuzzy entropy:Step 4:In this step, we calculate the aggregated information using all the logarithmic aggregation operators of spherical fuzzy sets.Step 5:We find the score value Step 6:By the definition, rank the alternatives In this section, we propose a new approach to decision-making based on the spherical fuzzy set. This approach will use data information provided by the decision problem only and does not need any additional information provided by decision makers, in order to avoid the effect of subjective information influencing the decision results. In the following, we will introduce a spherical fuzzy set decision-making matrix as indicated below.The Algorithmic Steps are shown in Assume that there is a committee that selects five applicable emerging technology enterprises (1) Augmented Reality (2) Personalized Medicine (3) Artificial Intelligence (4) Gene Drive (5) Quantum Computing To assess the possible rising technology enterprises according to the four attributes, which are(1) Advancement (2) market risk (3) financial investments (4) progress of science and technology To avoid the conflict between them, the decision makers gives the weight Since Step 2: Use the Step 3: The entropy of each attribute can be calculated by the following equation:Step 4: Now, we apply all the proposed logarithmic aggregation operators to collective spherical fuzzy information to find the aggregated information as follows:Case-1: Using logarithmic spherical fuzzy weighted averaging aggregation operator, we obtainedCase-2: Using a logarithmic spherical fuzzy ordered weighted averaging aggregation operator, we obtainedCase-3: Using a logarithmic spherical fuzzy hybrid weighted averaging aggregation operator, we obtainedCase-4: Using a logarithmic spherical fuzzy weighted geometric aggregation operator, we obtainedCase-5: Using a logarithmic spherical fuzzy ordered weighted geometric aggregation operator, we obtainedCase-6: Using a logarithmic spherical fuzzy hybrid weighted geometric aggregation operator, we obtainedStep 5: We find the score value Case-1: Score of aggregated information for the L-SFWA Operator, and we obtainedCase-2: Score of aggregated information for the L-SFOWA Operator, and we obtainedCase-3: Score of aggregated information for the L-SFHWA Operator, and we obtainedCase-4: Score of aggregated information for the L-SFWG Operator, and we obtainedCase-5: Score of aggregated information for the L-SFOWG Operator, and we obtainedCase-6: Score of aggregated inf ormation for the L-SFHWG Operator, and we obtainedStep 6: We find the best (suitable) alternative that has the maximum score value from set of alternatives The ranking of the alternatives are shown in the In this section, we give the comparison analysis on how our proposed logarithmic aggregation operators are effective and reliable to aggregate the spherical fuzzy information. Ashraf ,41 propoNow, we utilized a logarithmic spherical fuzzy weighted averaging operator to choose the best alternative as follows:The ranking of the alternatives using Ashraf  informatThe bast alternative is y Ashraf . Hence, In this paper, we have revealed a novel logarithmic operation of SFSs with the real base number


The goal of this study is to explore and evaluate the diagnostic values of myocardial blood flow (MBF), myocardial flow reserve (MFR) and relative flow reserve (RFR) obtained with low-dose dynamic CZT SPECT for patients with suspected or known coronary artery disease (CAD). Fifty-seven consecutive patients who underwent low-dose dynamic CZT SPECT and CAG were enrolled. MBF, MFR and RFR were calculated on the vessel level with dedicated quantitative software, and the difference and correlation of each parameter was compared according to the reference standard of stenosis ≥ 50% or ≥ 75% on CAG, respectively. ROC curves were made by stress MBF (sMBF), rest MBF (rMBF), MFR and RFR. The optimal cut-off values and corresponding diagnostic efficacy were obtained and compared with each other. Results indicated that when stenosis ≥ 50% or ≥ 75% on CAG was used as the reference standard at the vessel level, there was no statistically significant difference in rMBF between the negative group and the positive group (P > 0.05), and the sMBF and MFR in positive groups were significantly lower than that in the negative group . There was a moderate to significant correlation between sMBF and MFR, sMBF and RFR, MFR and RFR . These results indicate that low-dose dynamic CZT SPECT imaging can easily obtain the sMBF, MFR and RFR, and there is a good correlation among the three parameters, which has a certain diagnostic value for patients with suspected or known CAD, and is a useful supplement to the conventional qualitative or semi-quantitative diagnostic methods. Myocardial perfusion imaging (MPI) with single photon emission computed tomography (SPECT) is an important non-invasive imaging diagnostic tool in diagnosis, risk stratification, prognosis and efficacy evaluation for coronary artery disease (CAD) –5. The cIn recent years, the “milestone” progress of SPECT is the advent and clinical application of cardiac-dedicated SPECT equipped with cadmium-zinc-tellurium (CZT) of semi-conductor detectors, which has greatly improved the performance of SPECT equipment –10. CZT In the past, quantitative analysis of MPI mainly relied on positron emission computed tomography/computed tomography (PET/CT), but due to the expensive price and the limitation of the availability of positron perfusion imaging agents, it has not been widely used in clinical practice. With the popularization of cardiac-dedicated CZT SPECT, the quantitative analysis of MPI is highly expected again, and recently, some comparative studies , 16 havePatients with suspected or known CAD who underwent low-dose dynamic CZT SPECT MPI were continuously enrolled. Inclusion criteria: (1) The age is between 18 and 79 years old; (2) Have the invasive CAG data within 3 months before and after MPI examination, no revascularization treatment during the period; (3) Suitable for adenosine triphosphate (ATP) drug-stressed MPI and can tolerate the dynamic SPECT imaging process; (4) Signed the informed consent form; (5) The imaging data passed the quality control. Exclusion criteria: Highly unstable angina pectoris, old myocardial infarction, post-operative revascularization, atrioventricular block of degree II and above, sick sinus syndrome (except those who have a pacemaker), COPD , severe hypotension (systolic blood pressure < 90 mmHg), severe mitral or aortic valve disease, cardiomyopathy , CAG negative, but has clinical diagnosis of highly suspected coronary microvascular dysfunction (CMD) (such as syndrome X and microvascular angina) or coronary artery spasm, patients who fail to complete dynamic acquisition or complete dynamic acquisition but the image quality is not satisfactory, pregnant or lactating women. All patients were given informed consents and this study was approved by the Ethics Committee of TEDA International Cardiovascular Hospital.99mTc-MIBI. The technetium was provided by Beijing Senke Pharmaceutical Co., Ltd. or Tianjin HTA Isotope Pharmaceutical Co., Ltd. The MIBI was provided by Jiangyuan Pharmaceutical Factory of Jiangsu Atomic Energy Research Institute. The labeled radiochemical purity was ≥ 95%. Preparation for patients: within 24 h before the examination, strictly prohibit patients to drink coffee, tea, or any food containing caffeine and theophylline, and stop taking conventional medications for cardiovascular disease.The device was a cardiac-dedicated SPECT , equipped with a CZT detector and the radionuclide imaging agent was 99mTc-MIBI during rest and three times dose of that at stress. ATP-stress imaging was performed 1–4 h after rest imaging and the method refer to the literature [The acquisition used a “single-day” or “two-day” protocol: the “single-day” protocol was patients underwent CZT imaging with the administration of 185–296 MBq of terature . The “twAll dynamic list mode data was transferred to the MyoFlowQ  workstation and automatically reframed into a series of dynamic images: 10 s × 10 frames, 20 s × 5 frames, 60 s × 2 frames, 280 s × 1 frame; then called the CT attenuation correction data to complete the fusion alignment, axial adjustment, attenuation and scattering correction of the CT and SPECT images; automatically or manually adjusted the region of interest (ROI) of the blood pool curve input function and myocardial basal position, the dynamic curve and fitting curve of LV blood pool and LV myocardium were finally obtained. From this, rMBF and sMBF of LV 3-vessel regions were gained, and then, the MFR of the 3-vessel regions was calculated (MFR = sMBF/rMBF). Afterwards, the product of resting systolic blood pressure and heart rate, that is, RPP (rate pressure product), was used to correct rMBF. The RFR of a vascular region in the bullseye was defined as the ratio of the average sMBF of the myocardial segment within the vascular perfusion region of that branch to the sMBF of the normal reference myocardial region . The rouStandard Judkins method was used for CAG. Two cardiologists with more than 3 years of interventional experience assessed the stenosis of coronary arteries with diameter ≥ 2 mm , and using stenosis ≥ 50% or ≥ 75% as the criteria for judging the positive.T test; the relationship between quantitative parameters was analyzed by correlation. P < 0.05 was considered statistically significant.Used stenosis ≥ 50% and ≥ 75% on CAG as the reference standard for diagnosing CAD, the rMBF, sMBF, MFR, and RFR values of each vascular region in each group were obtained at the vessel level, and the following statistical analysis was performed: (1) compared the differences of quantitative parameters between the two standards; (2) calculated the correlation of quantitative parameters between two standards; (3) made ROC curves for rMBF, sMBF, MFR, and RFR under two standards, to obtain the best cut-off value and the corresponding diagnostic efficacy for obstructive CAD and compared them with each other; (4) excluded the patients with 3-vessels disease in each group (each major branch has at least one stenosis ≥ 50%) and repeated the process (3). All data were processed using IBM SPSS 17.0; measurement data were expressed as x ± sd, and comparison was performed using Fifty-seven patients with suspected or known CAD were included in this study, and their characteristics were shown in Table As shown in Table According to the standard of stenosis ≥ 50% of LAD, LCX and RCA on CAG, the patients were divided into 4 groups: non-obstructive atherosclerosis group , 1-vessel CAD group, 2-vessels CAD group and 3-vessels CAD group. The average and standard deviation of LV-rMBF, LV-sMBF and LV-MFR in each group were calculated. (1) non-obstructive atherosclerosis group: the values were 1.08 ± 0.27 ml/g/min, 2.33 ± 0.80 ml/g/min and 2.28 ± 0.86 ml/g/min, respectively. (2) 1-vessel CAD group: the values were 0.95 ± 0.17 ml/g/min, 1.67 ± 0.54 ml/g/min and 1.82 ± 0.67 ml/g/min, respectively. (3) 2-vessels CAD group: the values were 0.95 ± 0.21 ml/g/min, 1.47 ± 0.42 ml/g/min and 1.62 ± 0.54 ml/g/min, respectively. (4) 3-vessels CAD group: the values were 1.02 ± 0.07 ml/g/min, 1.12 ± 0.39 ml/g/min and 1.11 ± 0.32 ml/g/min, respectively. The comparison of LV-rMBF, LV-sMBF and LV-MFR in each group was shown in Fig. The relevant parameters of the ROC curve of each quantitative parameter under two reference standards were shown in Table In order to eliminate the possible effect of 3-vessel CAD on RFR, the AUC comparison of the quantitative parameters under two reference standards was measured again after excluding the patients with 3-vessels CAD. After excluding data from patients with 3-vessels CAD, using stenosis ≥ 50% as the reference standard, the AUC comparison results of sMBF and MFR: Z = 1.565, P = 0.1177; the AUC comparison results of sMBF and RFR: Z = 1.753, P = 0.0796; and the AUC comparison results of MFR and RFR: Z = 0.813, P = 0.4164. There was no statistical difference in these results. Similarly, after excluding data from patients with 3-vessels CAD, using stenosis ≥ 75% as the reference standard, the AUC comparison results of sMBF and MFR: Z = 1.686, P = 0.0917; the AUC comparison results of sMBF and RFR: Z = 0.605, P = 0.5449; and the AUC comparison results of MFR and RFR: Z = 0.239, P = 0.8168. There was no statistical difference in these results. The corresponding ROC curve is shown in Fig. A typical case who underwent quantification analysis was showed in Fig. According to the literature search, the present study is the first to use low-dose CZT SPECT continuous dynamic tomography imaging to obtain some new quantitative parameters of MBF, such as sMBF, MFR and RFR, to evaluate and compare their correlation and diagnostic value in patients with suspected or known CAD. In this study, we found that for sMBF, MFR and RFR, no matter which reference standard (stenosis ≥ 50% or ≥ 75%) on CAG, the parameter values in the positive group were significantly lower than those in the negative group, and there was statistical difference. At the vessel level, no matter using stenosis ≥ 50% or ≥ 75% on CAG as the reference standard, there was a moderate to significant correlation among sMBF, MFR and RFR. In the four groups of non-obstructive atherosclerosis group, 1-vessel CAD group, 2-vessels CAD group and 3-vessels CAD group, there was no statistical difference between any two groups of LV-rMBF, suggesting that it did not have diagnostic value, while sMBF and MFR tended to decrease gradually, and there was a statistically significant difference between any two groups of LV-sMBF and LV-MFR (expect in 1-vessel CAD group vs 2-vessels CAD group and 2-vessels CAD group vs 3-vessels CAD group). Through the analysis of ROC curve, sMBF, MFR and RFR showed better diagnostic performance, of which sMBF was the most prominent, no matter which reference standard of stenosis ≥ 50% or ≥ 75% on CAG. When the patients with 3-vessels CAD were excluded, there was no statistical difference in diagnostic performance among the three parameters.As we all know, conventional SPECT MPI plays an important role in non-invasive imaging diagnosis and evaluation of CAD –5. HowevIn general, when using SPECT MPI to diagnose CAD, one of the main factors affecting visual evaluation and semi-quantitative analysis is that we must choose a “normal” reference firstly, while the “normal” reference itself may not be “normal”. For example, (1) FOR the LM lesions, because the reduced blood flow is scattered in the LAD and LCX regions, compared with the “normal” RCA region, the semi-quantitative analysis leads to the underestimation of the lesion degree. If the RCA has obvious lesions at the same time, it may be further underestimated or even missed. (2) For 3-vessels lesions, the MBF in the 3-vessels regions has decreased in different degrees, while the regions with relatively low degree of perfusion defects are regarded as a “normal” reference, resulting in the extent of ischemia being underestimated. (3) If there are 3-vessels balanced lesions, due to the lack of contrast, it may lead to missed diagnosis. In this study, taking the cut-off values of MFR or sMBF obtained by ROC analysis as the diagnostic standard, the accuracy of judging 15 cases of 3-vessels lesions was 100% (15/15) and 73.3% (11/15), respectively, suggesting that the analysis of blood flow quantitative parameters has good value in multi-vessel lesions. In addition, due to the low energy of single-photon radionuclides, SPECT MPI artifacts caused by soft tissue attenuation have become a common problem, such as female dense tissue and/ or breast, as well as male diaphragm attenuation artifacts, is the common source of false positive diagnosis, but also the main reason for the poor specificity of conventional SPECT MPI diagnosis , 20. MPIPhysiological experiments have confirmed that for the normal coronary artery system, the peak blood flow under drug-stress can be increased by 3 to 5 times as much as at rest. Gould et al.  first us15O-water PET (r = 0.87). At present, FFR measured by pressure guide wire has been used as an invasive “gold standard” to judge whether epicardial coronary artery stenosis affects myocardial perfusion. In this study, we found that sMBF, MFR and RFR in the positive group were lower than those in the negative group, and with the improvement of diagnostic criteria, there was a trend of further synchronous decrease, and the correlation among the three parameters was moderate or above. ROC curve analysis showed that the diagnostic efficiency of the three parameters was very strong, which was consistent with the results of previous studies [RFR is defined by the ratio of a stenotic regional sMBF to normal perfusion regional sMBF obtained by quantitative MPI, which is considered to be similar to FFR, and can be used as an effective index to diagnose CAD . Early s studies , 28. How studies . At thisFirst, the sample size of this study is relatively small and due to the limitation of clinical technical accessibility, and it is not compared with the “gold” standard of FFR and index of microvascular resistance (IMR), which reflect epicardial coronary artery perfusion and microcirculation function. Second, obstructive CAD with microcirculation dysfunction cannot be distinguished by CZT SPECT quantitative parameters. Third, although clinically suspected CMD patients are enrolled in the exclusion criteria, due to the lack of IMR verification, it is not fully guaranteed whether CMD patients with atypical symptoms are included. Fourth, we admitted that although the recognized diagnostic cut-off value of MFR is 2.0–2.5, there is no unified diagnostic cut-off value for sMBF and RFR. Finally, due to different types of equipment and imaging agents, different physical correction factors, such as between CZT SPECT and PET/CT, between different types of CZT SPECT, between single-photon drugs and positron drugs, and between different single-photon drugs or positron drugs, the quantitative parameters obtained need to be further studied in detail.Our results demonstrate that new myocardial quantitative blood flow parameters of sMBF, MFR and RFR can be easily obtained by low-dose dynamic CZT SPECT, and the parameter values in the positive group were significantly lower than those in the negative group. There is a good correlation among the three parameters, which has a certain diagnostic values for patients with suspected or known CAD, and is a useful supplement to the conventional qualitative or semi-quantitative diagnostic methods.


Corneal hysteresis and corneal resistance factor are parameters that reflect the dynamic biomechanical properties of the cornea and have been shown to be biomarkers of corneal disease. In this genome-wide association study of over 100 000 participants, we identified over 200 genetic loci, all but eight novel, significantly associated with either one or both of these traits. In addition to providing key insights into the genetic architecture underlying normal corneal function, these results identify many candidate loci in the study of corneal diseases that lead to severe visual impairment. Additionally, using Mendelian randomization, we were able to identify causal relationships between corneal biomechanics and intraocular pressure measurements, which help elucidate the relationship between corneal properties and glaucoma. Corneal hysteresis (CH) and corneal resistance factor (CRF) are quantitative measures of corneal biomechanics. Both phenotypes are measured using the ocular response analyzer (ORA), a non-contact tonometer  that difCH and CRF have been implicated in several conditions of the eye. Previous work  has suggh2 = 0.77  included for CH and CRF analyses, respectively, following quality control . The mean age of participants was 57.3 (SD = 7.87), and 53.2% of participants were female. A summary of the participants measured phenotypes, stratified by age group, is provided in r = 0.82, P < 1.0 × 10−100) (P < 1.0 × 10−100), CRF—β = −0.015 mmHg/year , and on average men had lower CH  and CRF  than women.Phenotypically, CH and CRF were highly correlated ( 10−100) . Both CHr = −0.46, P < 1.0 × 10−100). CRF was positively correlated with IOPcc, albeit only to a small degree , despite CRF being adjusted to remove correlation with IOPcc  , despite 60.2% of POAG cases taking IOP-lowering medication, which has been reported to increase CH (Both CH and CRF were lower in primary open-angle glaucoma (POAG) cases than controls  were 1.06 (0.10) and 1.08 (0.11), consistent with expectations of polygenicity and large sample sizes (P < 5 × 10−08) with CH and CRF was observed for 13 945 and 20 020 variants, respectively  were previously associated only with CRF but were associated with both phenotypes in our analyses. Overall, in these analyses, 111 regions were associated at genome-wide significance with both CH and CRF. Over 12 million SNPs  were tested for association separately for CH and CRF. The genomic inflation factors  were λCHle sizes  indicatiCOL6A1, rs142493024, pCH = 7.5 × 10−98, pCRF = 1.1 × 10−101; COL6A2, rs1042917, pCH = 9.7 × 10−28, pCRF = 1.3 × 10−38; COL6A3, rs2645773, pCH = 6.6 × 10−31, pCRF = 4.5 × 10−36). Collagen type VI accounts for up to a quarter of the cornea’s dry weight  and within COL8A2  were associated with CRF. However, association of these markers did not reach genome-wide significance for CH .Collagen type VIII is an important component of the Descemet membrane  in the pCOL1A1) for CRF , though for CH, this marker only had suggestive association (P = 2.5 × 10−6). Meanwhile, SNPs adjacent to the gene for one of type V collagen’s subunits were associated with both CH and CRF .The stroma constitutes 90% of the corneal thickness and is primarily a complex of type I and type V collagen . SignifiTMCO1 , CAV2 , and DGKG . These phenotype-specific loci likely result from differences in phenotypic correlation between IOP with CH and CRF. Meanwhile, the CRF-specific loci are primarily collagen-related genes (as previously discussed), likely as a result of variation in the cornea’s physical structure having a greater influence over CRF than CH.Interestingly, a number of loci were specifically associated with CH and not CRF. These specific loci included several loci previously reported to be associated with IOP  such as:VCAN . Mutations within VCAN are responsible for the autosomal dominant vitreoretinopathy Wagner syndrome  based on data available from OMIM  summari and S4.FNDC3B , ZNF469 , MPDZ  and FOXO1 ; and FECD loci: TCF4 , ATP1B1  and SLC25A22 .Finally, many loci known to be associated with corneal diseases, including keratoconus  and FECDADAMTS17), rs12448432 (HAGHL), rs77542162 (ABCA6), rs77583146 (WNT10A), rs121908120 (WNT10A), rs1042917 (COL6A2) and rs139498917 (MAMDC2) were independently associated with both phenotypes; their missense coding effects make them strong candidates for causal loci. The minor allele for one of these SNPs in particular, rs139498917_A (MAMDC2), is associated with a very large, and clinically relevant increase in both CH and CRF , equal to a 0.62 standard deviation increase per allele for both.Conditional analysis refined these results, identifying 203 and 258 informative SNPs associated with CH and CRF, respectively. The Ensembl Variant Effect Predictor  identifiP < 2.5 × 10−4) (P < 0.05) with the same direction of effect. Two SNPs (rs534975221 and rs544072714) were not present in the replication dataset for CRF. From the remaining 253 markers that were tested, 26 SNPs from 20 distinct regions replicated at Bonferroni-adjusted significance (P < 1.98 × 10−4)  was conducted with a meta-analysis of two independent cohorts: TwinsUK and EPIC-Norfolk, as previously described . Though  × 10−4)  for CH,  × 10−4) , while aqCH = 9.0 × 10−4, qCRF = 9.1 × 10−3). There was noticeable enrichment for gene sets of systemic pathways such as the Gene Ontology  ) identified enrichment for collagen pathways including the ‘Collagens’  gene setOntology  ‘Skeletaet al.’s  and a non-coding RNA , upstream of ZNF469 on chromosome 16  is likely mediated through variation in gene expression. In total, there was significant association for expression of 86 genes with CH, and 107 with CRF, while 75/86 of the CH-associated genes and 96/107 of the CRF-associated genes are known to be expressed within corneal tissue (Using the same GTEx  fibroblaosome 16  and S14.l tissue  and S14.rg) were identified for CH and CRF with multiple phenotypic traits  and with CCT . Systemic trait correlations for CH and CRF were similar, such as forced vital capacity  and standing height . However, IOPcc correlations with CH and CRF were in reverse directions  and for POAG . The genetic correlation with IOPcc and POAG was stronger for CRF than CH, despite the reverse being true for IOPcc phenotypically.Genetic correlations . The biglycan protein forms a complex acting as a link between type II and VI collagen, with biglycan-deficient animal models having disarrayed collagen fibrils , these results are consistent with the core properties of these parameters. CH is representative of the cornea’s dampening capabilities which will be reduced by increased pressure, whereas CRF represents the resistance within the cornea which will increase when subjected to raised pressure. Interestingly, these results infer that CRF is not independent of IOP, despite the formula to derive it being designed to minimize IOP correlation and effects  is likely driven by the effect IOP has over CRF. In light of these results, further study is required to determine the utility and independence of CH as a risk factor for POAG progression  and outward (designated P2) applanation pressures . MeasurePOAG cases and controls were ascertained using ICD10 codes and self-reported questionnaire data. Use of IOP-lowering medication was self-reported.UK Biobank participants were genotyped on one of two arrays: the Affymetrix UK Biobank Axiom array, and the UK BiLEVE array. Imputation of additional variants was performed using a combined Haplotype Reference Consortium (HRC)  and UK10The CH and CRF measurements were used as the outcome variables in separate linear mixed model regressions, under the assumption of an additive model for allelic effects. Adjustments were made for age, sex and the first five principal components. These analyses were performed in BOLT-LMM  using a Phenotypic associations with age were tested in R  using a P < 5 × 10−8, customary for these analyses.In this paper, an ‘associated region’ was defined as a region with genome-wide significantly associated markers, separated from other associated regions by a minimum of 1 million base-pairs that are not significantly associated. Genome-wide significance for our study was set at An LD score regression intercept was calculated to identify any possible inflation  using thet al.  were excluded as they may have a common cause with the outcome (the MR independence assumption). Standard regression, penalized regression, robust regression, and penalized robust regression models were applied for these analyses with results indicating that the penalized models were the most suitable. The penalized models downweigh the contribution of variants with heterogenous causal estimates to the analysis; due to the inclusion of a relatively large number of instrument variables in these analyses, a penalized regression is more stable than a standard linear regression . The study also receives support from the National Institute for Health Research (NIHR)-funded BioResource, Clinical Research Facility and Biomedical Research Centre based at Guy’s and St Thomas’ NHS Foundation Trust in partnership with King’s College London. SNP genotyping was performed by the Wellcome Trust Sanger Institute and National Eye Institute via NIH/CIDR. M.S. is supported by the Wellcome Trust (Grant 206619/Z/17/Z).The EPIC-Norfolk study (https://doi.org/10.22025/2019.10.105. 00004) has received funding from the Medical Research Council (MR/N003284/1 and MC-UU_12015/1) and Cancer Research UK (C864/A14136). The genetics work in the EPIC-Norfolk study was funded by the Medical Research Council (MC_PC_13048).We are grateful to all the participants who have been part of the project and to the many members of the study teams at the University of Cambridge who have enabled this research. A.P.K. is supported by a Moorfields Eye Charity Career Development Fellowship.Supplementary_Figure_1a_ddaa155Click here for additional data file.Supplementary_Figure_1b_ddaa155Click here for additional data file.Suplementary_list_ddaa155Click here for additional data file.Supplementary_data_ddaa155Click here for additional data file.


Our systematic studies used materials that were likely to disclose differences with respect to anion type and their concentrations in the interlayer gallery. We assured to avoid any carbonate incorporation into the galleries for nitrate, chloride, iodide, and sulfate based Mg-Al LDHs. Furthermore, the comparative exfoliation experiments were conducted for fully hydrated samples with as similar particle morphology as possible. The exfoliation of nitrate Mg-Al LDH is far superior to similar clays with carbonate, sulfate, chloride, or iodide as charge balancing anions. Quantitative analysis of exfoliation yield for pre-treated, fully hydrated samples, shows an optimum composition for exfoliation into single nanosheets of around x ≈ 0.25, while double or triple layered sheets are encountered for other x-values. We observe a clear correlation between the expansion of the interlayer gallery due to progressing tilts of nitrate anions and water molecules out of the horizontal interlayer plane, suspension turbidity, and degree of exfoliation. The established correlations extends to nitrate Ni-Al LDH materials. We finally claim that morphology is a dominating parameter, with house-of-card morphology particles exfoliation far less than platelet-like particles. Hence, hydrothermal treatment may be favorable to enhance exfoliation yields.The exfoliation ability of nitrate based Mg MIIx1−MIIIx(OH)2][nA−]x/n·mH2O, are intensively studied as minerals and as synthesized compounds with highly tunable compositions. Their atomic arrangement is related to that of brucite, and the incorporation of higher valency cations. MIII is charge compensated by anions (nA−) in the interlayer gallery along with water molecules. Their stability covers at least the range 0.20 ≤ x ≤ 0.33 /2. Cationic compositions were determined by Microwave Plasma Atomic Emission Spectroscopy . CN analysis was performed at Ilse Beetz Microanalytisches Laboratorium, Germany. Transmission electron microscopy (TEM) images were obtained using a JEOL 2010F operating at 200 kV. All products were characterized by powder X-ray diffraction 2(NO3)x·mH2O, Nix1−Alx(OH)2(NO3)x·mH2O and Mgx1−Alx(OH)2(nA−)xn/·mH2O  powders prior to exfoliation studies. Samples were exposed to humidity in closed containers filled with a few mL of degassed water and argon. Exfoliation in formamide was thereafter performed immediately under ultrasonic treatment for 4 h . The low carbon level for the as-synthesized LDH is quite equal to that of the Mg-Al oxide calcined at 480 °C for 24 h. Probably, very minor amounts of carbonate is absorbed at surfaces during unavoidable exposure to low, yet non-zero, levels of air/moisture ; a = 3.0463 Å, c = 22.93 Å, representing the end point of the likely NO3–-OH− solid solution. The small OH− anions do not cause a molecular reorientation like the nitrate anions, and hence there is no major c-axis expansion, see c-axis in exactly the same x-composition interval as for the Mg-Al nitrate samples, also due to nitrate and water out-of-plane tilting. At pH = 10.0, the expansion is less, which again reflects incorporation of hydroxide anions to the interlayer gallery, We observe that for synthesis at high pH, the nitrate anions are (partly) replaced by hydroxide anions with Mgc-axes, −, I−, CO32−, and SO42− LDHs 2(nA−)xn/·mH2O with nA− = Cl−, I−, CO32−, SO42− are listed in d-value for (003) of 7.8 Å is characteristic for the carbonate-bearing hydrotalcite (x = 0.25) with flat-lying anions in the interlayer  with a maximum at x ≈ 0.25, The end turbidity varies from 500 NTU for Mg-rich nitrate samples to a minimum of <20 NTU for c-axis , c-axis expansion, and degree of exfoliation. For LDHs with Cl−, I−, CO32−, or SO42− as interlayer anion, the degree of exfoliation was in all cases low, 15–32%, There is a close correspondence between the degree of exfoliation and the length of the Based on the expansion of the gallery on increasing nitrate content, one could by analogy to Mg-Al nitrate LDHs also expect good exfoliation properties for Ni-Al nitrate LDHs. However, we find the exfoliation properties to be inferior for Ni-Al LDHs , with thx = 0.25 nitrate Mg-Al LDHs show well dispersed nanosheets with disc like morphology, 30–40 nm in lateral dimensions, and 0.70 ± 0.07 nm heights (average 10 particles). Typical tapping mode AFM images are shown in x = 0.20 and 0.33, the observed disc thickness is higher; 2.4 ± 0.7 nm and 2.1 ± 0.7 nm, respectively (standard deviation based on ten particle heights). The observed minor discrepancies in the compositional variation of turbidity and degree of exfoliation is possibly caused by different thicknesses of the obtained nanosheets. When considering the AFM data, the degree of exfoliation must be kept in mind. The concentration of nanosheets on the mica surface is larger for x = 0.25 and 0.33 than for the poorly exfoliated x = 0.20 sample. For x = 0.20, major amounts of large LDH particles settle during the high-speed centrifugation. Note that the AFM images of the nanosheets represent just a small percentage of the material that underwent the exfoliation protocol.Tapping mode AFM data for exfoliated Our earlier studies  showed tx1−Alx(OH)2(nA−)x/n·mH2O clay materials and their ability to undergo exfoliation. We identify these once other parameters are sufficiently constrained, approaching one-parameter like investigations. In this respect, control of anion purity, water saturation of interlayer gallery, as well as maintaining close similarity in morphology is essential. We observe clear correlations between crystal structure and interlayer chemistry of Mg1 polytype stacking remains to the best of our knowledge unchanged for different M(III) contents in the Mg-Al and Ni-Al LDH systems. However, we are aware from (unpublished) total scattering and PDF (pair distribution function) data that certain smaller, yet significant, variations remain unexplained. Hence, certain secrets are still undisclosed.When turning to details, the average 3Ra-axis vary more or less identically with x for the various anion systems. Yet, these systems differ significantly; (i) first by the anion charge; monovalent versus divalent  with implications on anion concentration and on electrostatic interactions towards the brucite layered backbone; (ii) second, by the anion size and geometry which influence anion orientation and thereby length of the c-axis, especially at high anion concentrations; and (iii) to a lesser extent, but nevertheless, the hydration level . This probably proves a more homogeneous distribution of water molecules and nitrate anions, with respect to concentration and to tilt angles. This may be caused by the larger platelet size, and the lack of interfaces towards interwoven crystallites. We suggest that the hydrothermal treatment initiates a recrystallization process towards the more well-defined LDH materials. Possibly, the genuine 3R1 polytype material properties are only shown for platelet like morphology, and remains hidden for house-of-card structures. We speculate whether even poorly exfoliating Mg0.75Al0.25(OH)2(nA−)/n0.25·mH2O  can possess improved exfoliation properties if optimized  during hydrothermal post treatment. It is interesting to note that the degree of exfoliation of Nireatment . Obviousx ≈ 0.25; exfoliation into double or triple sheets is typically encountered for other x-values; (iii) the end turbidity for x = 0.25 samples with nA− = Cl−, I−, CO32−, and SO42− is consistent with poor capability towards exfoliation; (iv) modifying the morphology by hydrothermal treatment into more platelet like crystallites have a positive effect on exfoliation ability.In summary: (i) For nitrate based Mg-Al LDHs, humidity pre-treatment has a positive effect on exfoliation, however, the improvement is small and probably not required for still achieving facile exfoliation; (ii) nitrate bearing LDHs exhibit a sufficiently high degree of exfoliation in formamide being useful for practical purposes; maximum amounts of single nanosheets are obtained for


NCPs included atrazine, carbaryl, and carbofuran were extracted with a dichloromethane/acetone mixture (50:50 v/v), while maneb was extracted by intensive shaking the sample with acetone (1:1 v/v) and ethylenediamine-tertraacetic acid. The NCPs were identified by a dual mass- spectrometry (GC-MS/MS). The total content of individual OCPs ranged from 0.61 to 1031.64 µg kg−1, while the NCP concentrations were significantly lower, from 0.01 to 43.92 µg kg−1. DDTs were detected in all soils samples  > p,p’DDT (18.23 µg kg−1) > p,p’DDE (4.06 µg kg−1), while HCHs were only in 4% of the analyzed samples (β-HCH (339.55 µg kg−1) > α-HCH (96.96 µg kg−1) > γ-HCH (3.04 µg kg−1)), but in higher values than DDTs. Among NCPs, higher concentration was observed for carbaryl (<0.01–28.07 µg kg−1) and atrazine (<0.01–15.85 µg kg−1), while the lower for carbofuran (<0.01–0.54 µg kg−1). Maneb was not detected in analyzed soils. Assessment of the level of soil pollution based on Polish regulations indicated that several percentages of the samples exceeded the criterion for OCPs, such as ∑3DDTs  and HCH congeners , while NCP concentration, such as for atrazine, carbaryl and carbofuran were below the permissible levels or were not detected in the analyzed soils, e.g., maneb. The obtained results indicated that residues of the analyzed pesticides originate from historical agricultural deposition and potentially do not pose a direct threat to human and animal health. The behavior and persistence of pesticides in the soils depend on their properties. Significantly lower NCP concentration in the soils resulted from their lower hydrophobicity and higher susceptibility to leaching into the soil profile. OCPs are characterized by a high half-life time, which affect their significantly higher persistence in soils resulting from affinity to the soil organic phase.Pesticides belong to a group of xenobiotics harmful to humans and wildlife, whose fate and activity depends on their susceptibility to degradation. Therefore, the monitoring of their residue level in agricultural soils is very important because it provides very valuable information on the actual level of soil contamination and environmental risk resulting from their application. The aim of this study was to evaluate contemporary concentrations of organochlorine (OCPs) and non-chlorinated pesticides (NCPs) in arable soils of Poland as an example of Central and Eastern European countries. The results were assessed in relation to Polish regulations, which are more restrictive compared to those of other European countries. The sampling area covered the territory of arable lands in Poland (216 sampling points). The distribution of sampling points aimed to reflect different geographical districts, conditions of agricultural production, and various soil properties. The collected soil samples were extracted with organic solvents in an accelerated solvent extractor (ASE 2000). The OCPs, including α-HCH, β-HCH, γ-HCH, and p,p’DDT, p,p’DDE, and p,p’DDD, were extracted with a hexane/acetone mixture (70:30  The use of pesticides significantly influences the intensification and efficiency of agriculture production ,2. DespiThe fate of pesticides in soil depends on many factors related to physical, chemical, and photochemical processes, as well as biological transformation ,8. TheirPesticide residues occurring in the soil constitute mainly toxic chemicals that adversely affect the environment . Their eAgriculture is a very important economic sector in Europe. In Poland, rural areas cover over 95% of the total area of the country . In 2018The environmental behavior of new-generation pesticides are under the requirements of the REACH directive , but in many countries content of highly persistent and potentially toxic chlorinated pesticides such as: HCHs, DDTs, or drins  is still under control.In 2016, the ordinance of the Polish Ministry of the Environment was amended, which indicates the toxic compounds causing risk to human health and soil whose content should be controlled . AccordiOur aim was to evaluate contemporary OCP and NCP concentrations in the arable soils of Poland as an example of Central and Eastern European countries. Results were assessed in relation to current Polish regulations.KCl value ranging from 3.1 to 7.4 (mean = 5.0), maximum clay content (fr < 0.002 mm) of 47% with a mean at 5.2% (CoV = 111%), and silt content ranging from 2% to 83%. TOC concentrations were diversified from 3.6 to 38.4 g kg−1 (CoV = 44.6%), indicating the various degrees of supply inflow and accumulation of organic matter in agricultural soils. Similarly, TC and TN  with mean TC/TN ratio equaling 9.4 (CoV = 18.5%) indicated a varying degree of organic matter decomposition [Generally, the basic physicochemical properties of soils exhibited relatively uniform values. The obtained data results  had a siposition . Resultsfr < 0.00 mm of 47position ,28,29,31−1. ∑3DDT compounds were detected in all soil samples (100%), and their concentrations were relatively uniform (CoV = 144%). The content of individual isomers was diversified, such as pp’DDT (0.12–202.68 µg kg−1), pp’DDE (<0.10–79.87 µg kg−1), and pp’DDD (<0.10–267.52 µg kg−1), which accounted for 35%, 8%, and 46% respectively, of total OCPs or ∑3DDT. Exceeding the permissible DDT content sum specified at the 120 µg kg−1 level [−1 with interquartile range 1.22-54.38 µg kg−1. The average contents of HCH congeners were as follow β-HCH (339.55 µg kg−1) > α-HCH (96.96 µg kg−1) > γ-HCH (3.04 µg kg−1). According to the results, HCH residue concentration exceeded the limit values included in Polish regulations in some soil samples  [−1 [−1 [−1 [−1 [−1) in a research conducted in 2005 [Statistical evaluation of OCPs concentrations in the soils is described in −1 level  was onlyµg kg−1) . OCP cong−1) [−1 ), German [−1 [−1 ), Spain  [−1 [−1 ). Furthe in 2005 . However in 2005 ,36The relatively high DDT residues in most monitored soils can be a consequence of permissible application of these compounds before 1970s, when the use of this pesticide was finally restricted ,27,29,31Evaluation of HCH residue concentration indicated that the HCH sum was less widespread than the DDTs sum in the study area, although HCH had been more abundantly used in agricultural sector in Europe. Generally, HCHs have higher biodegradability and vapor pressure as compared to DDT that can lower their accumulation in soils. The highest percentage proportion of HCHs was contributed by β HCH, followed by α-HCH, and γ-HCH. Among all HCH congeners, β-HCH exhibited high persistence and very poor susceptibility to degradation in soils ,27. Thes−1) to 43.92 µg kg−1. The interquartile range was narrow (0.3–1.02 µg kg−1) with an average value of 1.17 µg kg−1. The share of individual compounds in total NCP content was diversified (CoV = 343%). Higher concentration was observed for carbaryl (<0.01–28.07 µg kg−1) and atrazine (<0.01–15.85 µg kg−1) while lower for carbofuran (<0.01–0.54 µg kg−1). Maneb was not detected in any of the analyzed soils or its content was highly below the limit of detection. In all soils, the concentrations of NCP compounds did not exceed the permissible levels defined in the national regulation, namely for carbaryl: 200 µg kg−1, carbofuran: 200 µg kg−1, maneb: 200 µg kg−1, atrazine: 50 µg kg−1 [Statistical evaluation of NCP concentrations in soils is described in  µg kg−1 . The var−1 [−1 [Generally, the concentrations of individual NCPs in Polish soils are comparable with recorded results for other countries. Most studies concern atrazine which was highly detected in soils of Canada , Cro−1 [−1 ), and Ch−1 [−1 ). Despit−1 [−1  found th−1 [−1 . Atrazin−1 [−1 , Brazil −1 [−1  and Chin−1 [−1 , posing −1 [−1  indicate−1 [−1 .o/w) for carbaryl was five times higher in clay-rich soils (Ko/w = 235) than in soils with organic matter content exceeding 20 g kg−1 (Ko/w = 54.2). De Oliveira et al. [The carbaryl concentration in Polish soils prevailed among all determined NCPs. Its amounts in soils result from the fact that carbaryl was used as a substitute for OCPs and it is one of the most commonly used insecticides still used in the United States . Differea et al.  found tha et al. . Additio1 Ko/w = .2. De OlThe concentration of carbofuran in analyzed Polish soils was very low, and this compound was only detected in four soil samples (about 2% of soils). This confirms the fast dissipation time of carbofuran in natural field conditions and its high susceptibility to degradation. These results are in agreement with the observations of Wang et al. , Otieno Maneb, a polymeric complex of manganese (Mn) with ethylene bis dithiocarbamate  was not The relationship between soil physicochemical properties and pesticide residues concentrations is shown in Results indicate that pesticide residue formation and its persistence may also depend on other agricultural and environmental factors . Persistence of pesticides in soils was found to increase with increasing its concentration, whereas mineralization, and the formation of degradation products and bound residues, decrease at higher concentrations . The forThe research was conducted as a part of the national program: “Monitoring of the chemical properties of arable soils in Poland in 2015–2017 , includi2, where the final sample was a mixture of 20 subsamples. Soil samples were air-dried (48 h at 20 °C), homogenized, sieved (2 mm sieve-mesh) and stored in the dark for further characterization.The sampling area covered the arable lands in Poland , total carbon content (TC), total organic carbon content (TOC) as well as total nitrogen content (TN) were measured. The pH was determined according to the PN-ISO 10,390 by potentiometric method and soil suspension in 1 mol l−1 KCl solution (1:2.5 m V−1). Clay content was analyzed according to the PN-R-04032 via the aerometric method, while TN and TC were determined by dry combustion in a Vario Macro cube CN elementar analyzer . TOC content was determined according to the PN-ISO 14,235 by sulfochromic oxidation with titration of excess K2Cr2O7 with FeSO4(NH4)2SO4·6H2O.The selected soil physicochemical properties included analysis of pHv/v). Soil extracts were concentrated, and the solvent was exchanged to hexane. The concentrated extracts were passed through a glass column packed with glass wool, 2 g of deactivated alumina oxide (15% in MilliQ water), and 1 cm of anhydrous sodium sulfate; then it was eluted with 20 mL of petroleum ether. The solvent was exchanged to hexane following vacuum evaporation, and the extracts were concentrated to 1 mL. Determinations of DDTs and HCHs were performed using gas chromatography with microelectron capture detector (GC-µECD) system . Quality control measures included analysis of certified reference material , duplicate matrix samples, a solvent blank sample as well as surrogate and internal standards. As the surrogate standard, PCB 155 compound  was used by soil spiking (10 g of soil was fortified by 10 µL of PCB 155 in a concentration of 20 µg mL−1), to estimate and control the matrix effects on the obtained results in the analyzed samples.OCPs analysis comprised 3 congeners of HCH  and DDT —Additionally, PCB 207  was used as the internal standard (added to the sample extract directly before injection), which allowed to control the instrument and injection parameters of GC-µECD.n-hexane were analyzed in a single run using a gas chromatograph (Agilent 6890) equipped with a 63Ni microelectron capture detector (µECD) and Agilent 7683B Series autosampler . Samples were injected to a deactivated Agilent single-taper liner (p/n 5181-3316) in splitless mode at the injection-port temperature of 225 °C. DDTs were separated on a DB-5 capillary column . The remaining operating conditions of GC-µECD apparatus are presented in OCPs soil extracts concentrated in −1 level. The detection limit value was adopted as the minimal value of the content of the measured OCPs compounds. More detailed analysis methodology was described by Maliszewska–Kordybach et al. [The basic validation parameters were determined by analyzing the certified reference material  in 10 sample replicates and 2 repetitions of the injection of the same sample. Precision expressed as relative standard deviation (RSD), was in the range of 5–10%, and the recovery for individual compounds for certified reference material-CRM 847 was in the range of 71–82% for the DDTs, and 67–89% for the HCHs. The limit of detection (LoD) for DDT and HCH compounds was at the 0.10 μg·kgh et al. .v/v) in an ASE200  apparatus. Clean-up of the concentrated extract was performed using dichloromethane:ethyl acetate elution (50:50 v/v) in a glass column packed with glass wool, 2 g of deactivated alumina oxide (15% in MilliQ water), and 1 cm of anhydrous sodium sulfate. The solvent was exchanged to ethyl acetate following vacuum evaporation, and the extracts were concentrated to 1 mL.NCPs analysis included determination of atrazine, carbaryl, carbofuran, and maneb  in two sv/v) in an ultrasonic bath. To efficiently dissolve maneb in acetone, chelating agents such as ethylenediamine-tertraacetic acid (EDTA), were additionally used to complex the maneb molecules and strip away the manganese bivalent agent (derivatization processes). The released ethylene-bis-dithiocarbamate (EBDTC) anions were stabilized by the addition of ascorbic acid to prevent their decomposition processes. The obtained extracts were purified in the column with activated carbon (to remove particles of organic matter), and then the extracts were concentrated by evaporation to 1 mL. Samples were analyzed on GC MS/MS (full SCAN scan ion monitoring mode) up to 5 days after their extraction due to the possibility of extraction product decomposition. Maneb was identified and quantified by comparing the retention time peaks of the standard solutions. The efficiency of the derivatization process was determined with analyses of the 10 samples of the prepared standard solutions ; on average 87% with RSD at 4%. The recovery of the applied method was determined by maneb addition to the soil at level of 400 µg kg−1 which corresponds to a double limit value of the permissible maneb content in Polish agricultural soils . The spiked soil sample was homogenized , divided into 10 sub-samples and subjected to the extraction procedure. Method recovery was noted at the level of 78%, while method repeatability at 6%. Indeterminate and random errors were not detected in the developed methods. The correctness of the method was confirmed by HPLC .Maneb was extracted according to methodology described in the Handbook of Pesticides-Methods of Pesticides Residue Analysis  by intensive shaking of the soil sample with acetone (1:1 −1), to estimate and control the matrix effects in the analyzed samples. Additionally, PCB 207  was used as internal standard (added to the sample extract directly before injection) that allowed one to control instrument and injection GC MS/MS parameters.Similarly to OCP analysis, we used the PCB 155 compound  as surrogate standard by soil spiking , equipped with an Agilent 7000C detector and Agilent 7693 Autosampler. −1 level. The detection limit value was adopted as the minimal value of the content of measured NCPs compounds.The precision of the method expressed as a relative standard deviation (RSD) was in the range of 3–10% and the recovery for individual compounds for certified reference material BNA in the soils—PT  was within 86–90%. The limit of detection (LoD) for individual NCPs compounds was at the 0.01 µg kgReceived data were analyzed by basic statistical parameters, namely, minimum (Min), maximum (Max), median (Me), lower (LQ), upper quartile (UQ), standard deviation (SD), coefficient of variation (CoV), kurtosis and skewness. The normal distribution of the results was checked by chi-squared test. Principal component analysis (PCA) was performed to provide an overview of the relation pattern between OCP and NCP concentrations in soils and soil properties. PCA was used to evaluate the inter-relationships in measured variables in order to identify the essential structure of their correlations.Contamination of arable soils in Poland representing Central and Eastern Europe, by organochlorine and nonchlorinated pesticide residues was generally low, comparable to contamination levels observed in the rural areas of other European countries. Assessment of the level of soil contamination based on Polish regulations  indicate


Batrachochytrium dendrobatidis (Bd) a devastating, panzootic pathogen of amphibians. Although micrograzers consumed zoospores (∼3 μm), the dispersal stage of chytrids, not all species grew monoxenically on zoospores. However, the ubiquitous ciliate Tetrahymena pyriformis, which likely co-occurs with Bd, grew at near its maximum rate (r = 1.7 d–1). A functional response (ingestion vs. prey abundance) for T. pyriformis, measured using spore-surrogates (microspheres) revealed maximum ingestion (Imax) of 1.63 × 103 zoospores d–1, with a half saturation constant (k) of 5.75 × 103 zoospores ml–1. Using these growth and grazing data we developed and assessed a population model that incorporated chytrid-host and micrograzer dynamics. Simulations using our data and realistic parameters obtained from the literature suggested that micrograzers could control Bd and potentially prevent chytridiomycosis (defined as 104 sporangia host–1). However, simulated inferior micrograzers (0.7 × Imax and 1.5 × k) did not prevent chytridiomycosis, although they ultimately reduced pathogen abundance to below levels resulting in disease. These findings indicate how micrograzer responses can be applied when modeling disease dynamics for Bd and other zoosporic fungi.Free-living eukaryotic microbes may reduce animal diseases. We evaluated the dynamics by which micrograzers (primarily protozoa) apply top-down control on the chytrid  Bacterial growth was prevented by the addition of antibiotics . Note, antibiotics may have small detrimental effects on protozoan swimming speed  was centrifuged , the supernatant removed, and the pellet resuspended in autoclaved Volvic® mineral water to a concentration >1.50 × 105 ml–1 . Resuspended cultures were examined microscopically (40×) to ensure zoospores were motile. Bacterial growth was prevented with antibiotics, as above.Prior to introducing micrograzers, ® water to remove bacteria. Then 5 to 8 individuals, dependent on micrograzer size, were added to a 10 ml well containing the Bd suspension. Parallel treatments containing only sterile Volvic® water were used to assess mortality rate in the absence of prey, i.e., starvation rates. All treatments  were replicated in triplicate . To assess growth rate , the number of gazers in each well was determined microscopically, using a dissection microscope, after 2 or 3 days (depending on the observed change in abundance). Then, new Bd suspensions were prepared (as above), and micrograzers were transferred to these, maintaining Bd abundance. If micrograzer numbers decreased (net death occurred) over the incubation, then all individuals were transferred, but if numbers increased (net growth occurred) then the initial number was transferred. Cells death was estimated by their disappearance  was determined over each incubation period, as r = ln(Nt/N0)/t, where N0 and Nt are the micrograzer abundance on the initial and final day, respectively, and t is the incubation period (2 or 3 days); to determine growth rate across all transfers (up to 14 days), the average of these was obtained. When micrograzer numbers decreased between transfers, mortality rates  were determined as slope of ln numbers over the entire incubation period. To assess if growth (or death) rate differed between treatments  a two tailed t-test was conducted (α = 0.05).When numbers increased between transfers, growth rate (Tetrahymena pyriformis as: (1) it grew rapidly on Bd zoospores (see section “Results”) and therefore clearly consumed and assimilated zoospores; (2) it is a model organism for which there are substantial data (see section “Discussion”); and (3) it is common, globally, in habitats where Bd may occur (see section “Discussion”). Prior to determining ingestion rate, T. pyriformis was acclimated with zoospores for >10 h. To do so, the ciliates were first removed from H-broth by centrifugation  and then resuspended in 10 ml of autoclaved Volvic® water. To obtain only zoospores, a centrifuged Bd culture (as above) was filtered through a 5 μm Nitex® mesh. Zoospores were then added to the water containing ciliates, to a total volume of 20 ml (resulting in ∼106 zoospores ml–1), with antibiotics (as above). This acclimation had no negative effects on the ciliates: after 10 h, zoospore abundance had substantially decreased and ciliate abundance increased (indicating the ciliates were feeding and growing), the ciliates behaved similarly to when grown on H-broth , and their cell size and shape were similar to when grown on H-broth.Our study focused on TM, Thermo Fisher Scientific, United States) acted as a surrogate for Bd zoospores which are 3–5 μm (3 ml–1 to 106 ml–1 (see section “Results”), were prepared in autoclaved Volvic® water and vortexed prior to use, ensuring mono-dispersion. An aliquot (0.5 ml) of the acclimated ciliate culture (>30 micrograzers) was added to 1 ml of Volvic® water with beads, at various concentrations [with more measurements at low abundances  at each prey concentration.To determine ingestion rate on spore-sized particles, 3 μm fluorescent polymer microspheres , was determined by fitting a Type II functional response to the data: I = Imax∗Z/(k + Z), where Imax (Z min–1) is the maximum ingestion rate and k is the half saturation constant (Z ml–1). The response was fit using the Marquardt-Levenberg algorithm ; this algorithm is appropriate for describing such biological data sets (The relationship between ingestion rate and zoospore abundance (ata sets .Bd infection populations we developed and applied the following model that couples a reduced version of the Bd-load model (T. pyriformis were used to represent micrograzers (see the Discussion for a justification to focus on this species). Following logic outlined in the Introduction, the model describes the infection load on a single host and, as a proxy for the waters surrounding the host, only considers a volume of 10 ml around that host, where zoospores and micrograzers reside. As a metric to predict chytridiomycosis, it assumes that a sporangia load of 104 per host results in host mortality ; Z is the zoospore abundance (ml–1); y is the per capita spore-host encounter rate; v is the fractional likelihood of spore infection per encounter; σ is the per capita sporangia mortality rate; η is the per sporangia spore-release rate; and μ is the per capita spore mortality rate , where grazing (I) is dictated by the functional response ; e is the abundance-based conversion efficiency, determined assuming a biomass-based estimate of e is ∼0.1  that implicitly assumes that in the absence of zoospores the micrograzer population is maintained by the presence of other potential food sources; hence we model potential increases in micrograzer abundance over and above this minimum, dependent on consumption of Bd zoospores. Estimates of d and b are based on our unpublished observations when Tetrahymena was exposed to poor food conditions. Then, Eqs. 2, 3 were coupled to include spore loss by micrograzers ( is ∼0.1  and biov–1 (1 sporangium ml–1), 100 zoospores ml–1, and 1 micrograzer ml–1 . For Bd, we applied parameter values that were within the range explored by All model runs (100 d) were initiated with 10 sporangia hostT. pyriformis to control Bd. Then, we assessed the extent to which micrograzers that are inferior to T. pyriformis could control Bd, through exploration of micrograzer parameter space. Inferior micrograzers had reduced maximum ingestion rate (up to 0.5 × Imax of T. pyriformis) and increased half saturation constant (up to 2 × k of T. pyriformis); see Bd, we examined the maximum abundance (over the 100 days) and the abundances at 50 and 100 days of S, Z, and G.We first performed simulations to assess the ability of –1  higher than in water alone; (2) for the ciliates Urocentrum turbo, Blepharisma sp., and Oxytricha sp. and the rotifer Philodina sp. there was no significant difference between death rate with or without Bd; (3) for the rotifer Brachionus calyciflorus growth rate initially increased  followed by death, and for the ciliates Paramecium aurelia and P. caudatum  and near its maximum rate under any conditions.All of the micrograzers can be maintained in laboratory cultures, with maximum growth rates ranging from ∼0.4 to 2 d–1 , and all–1 . When feesponses : (1) forcaudatum  the growo growth , 4 for twth rate , which wT. pyriformis grew on zoospores alone it was clear that this ciliate ingested, digested, and assimilated Bd zoospores. Zoospores were also observed in T. pyriformis, in the food vacuoles of the ciliate, under 40 × magnification, further supporting their consumption. Ingestion rate using beads as a surrogate for Bd zoospores followed a typical Type II (rectangular hyperbolic) functional response (R2 = 0.82), with Imax = 1.63 × 103 ± 98 (SE) prey d–1 and k = 5.75 × 103 ± 1.38 × 103 (SE) prey ml–1.As Bd occurred when parameters for the micrograzer (T. pyriformis) were included in the model , and Bd was virtually eradicated by 100 days  and half the maximum ingestion rate (Imax) of T. pyriformis  and >1.5 × k (∼9 × 104 ml–1) were not capable of preventing sporangia per host exceeding lethal levels of 104 per host  by reporting the maximum abundance and the abundances at 50 and 100 days of zoospores, sporangia, and micrograzers. Across all parameters explored, the micrograzer population provided top-down control of 100 days . Howeverundances  and persundances , indicatbundance , in respBatrachochytrium dendrobatidis (Bd). Several micrograzers are known to consume Bd zoospores , while P. aurelia, and P. caudatum cannot, again possibly due to a lack of nutrients such as essential fatty acids and B-vitamins  lead to control of Bd populations. These findings argue that Bd-host dynamics should now be examined in a wider food-web context, with mixed an assemblage of microgazers sustained by Bd and a wider range of natural food sources.Our analysis, therefore, suggest that not all micrograzers would be capable of or equally proficient at controlling e feeder  others sciliates . Likely,e growth . Our anaTetrahymena is common in shallow waters, living near sediments, where it consumes bacteria and other microbes , but again we were not successful. Consequently, ingestion estimates relied on the uptake of fluorescent beads as surrogates for Bd, which may underestimate rates . To our knowledge, this is the first time a functional response on Bd sized particles has been obtained for any Tetrahymena species: the estimates of Imax and k are within the range of those obtained for other ciliates, although the k-values are on the lower end of the spectrum , top-down control may be absent, and our analysis suggests that Bd may thrive, resulting in chytridiomycosis. Consequently, assessing the abundance of micrograzers in waters where chytridiomycosis occurs or is predicted seems warranted.Contributions of micrograzers to disease dynamics are also likely to have a highly site-specific component, due to their dependence on environmental factors . For insTetrahymena and Paramecium are already common if not ubiquitous in aquatic environments and are simple and inexpensive to grow in large quantities (Bd in situ. However, such manipulations could have detrimental, ecosystem-changing effects (Finally, as both antities , they maantities  that by  effects . Extensihttps://doi.org/10.6084/m9.figshare.13516577.v1.The data supporting the conclusions of this article have been made available by the authors, without reservation. They can be found at: HF, JJ, and AH conducted the laboratory work, under the guidance of DM. HF, AF, DD, and DM devised and conducted the modeling. TG and MF provided specific guidance on host and chytrid biology, respectively. All authors provided essential input into the conceptualisation of the study, design of the experiments, contributed to writing, and revising the manuscript.The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.


There is a shortage of dental hygienists for dental clinics in Japan. An ideal solution would be for dormant dental hygienists to re-enter the workforce. In this study, we identified the obstacles preventing these dental hygienists from re-entering the workforce. The Japan Dental Hygienists’ Association surveyed all 16,113 members about their working conditions. Among the 101 items in the questionnaire, 11 items specifically targeted the reasons why dental hygienists leave their jobs. Among 8780 responses (54.5%), 1063 were from members who had resigned from jobs as dental hygienists. Three hundred and fifty-five (34.4%) answered “Yes” to the question “I would like to return to work if conditions are satisfactory.” The most frequent cause for leaving a job was” Childbirth and child-rearing” (16.9%). “Working status/working hours” (15.7%) was the main obstacle to re-entry. Furthermore, dental hygienists with intentions to re-enter decided to leave their jobs most frequently because of “Childbirth and child-rearing” and “Working status/working hours.” Improvement of the social support system for dental hygienists is required to ensure a sufficient supply of dental health services. Japan is a super-aging society with the proportion of people aged over 65 years being 28.4%, while the working-age population (15–64 years old) accounts for 59.5% .Japanese law declares that the main task of dental hygienists is the improvement of oral health nationwide. The scope of the work of dental hygienists is oral care and health guidance under the supervision of a dentist, cleaning teeth, the mechanical removal of deposits on the tooth surface over the gingival margin, and assistance with dental treatment. Their dental treatment duties have expanded. There is a strong and increasing demand for oral healthcare in Japan, particularly for older adults. Pneumonia is one of the most common causes of death in Japan, and the crude death rate has been increasing. According to a demographics survey conducted in Japan, aspiration pneumonia resulted in 40,385 deaths in 2019, the sixth most common cause of death ,7,8, andIn addition, perioperative dental care has been introduced to the Japanese medical insurance system. Perioperative oral care management is an effective way to reduce disease complications and hospitalization costs. Many hospitals do not employ dental hygienists. Dentists or dental hygienists from private dental clinics visit hospitals for the oral care management of hospitalized patients. However, this scheme has not yet been thoroughly addressed.The role of dental hygienists is vital for the prevention of these diseases. However, the number of dental hygienists per head of population is about 1 in 1000. The dental hygienist workforce is not sufficient to provide dental health services under the Japanese national medical insurance system. According to the national survey of Japan, 132,629 dental hygienists out of approximately 200,000 subjects who had licenses worked in 2018 [In Japan, dental services are sustained mainly by private dental clinics. As of 2018, there were 68,500 dental clinics in Japan . A totalA survey of the working conditions of dental hygienists is conducted by the Japan Dental Hygienists’ Association every five years. This survey includes items to investigate why dental hygienists leave the professional field. This study aims to identify the obstacles faced by dental hygienists in re-entering their profession and propose countermeasures for supporting re-entry by statistical modeling.The Japan Dental Hygienists’ Association has been surveying the Employment Status of Japanese dental hygienists every 5 years since 1981. Questionnaires were distributed to all members of the Japan Dental Hygienists’ Association on 16 October 2019 by postage-paid mail with a return envelope. The questionnaires received before the 11 November were used for the analysis. The questionnaire analyzed in this study is provided as The questionnaire consisted of 101 items concerning demographic factors, employment situation, job description, and willingness to work.There were ten specific items targeted at dental hygienists who were leaving their jobs as dental hygienists. In this study, we analyzed these ten specific items.(1)Why did you decide to leave the workplace where you were last working as a dental hygienist? Select all that apply and mark the best answer separately.These items are as follows:1. Dissatisfaction with work content, 2. Payment/welfare, 3. Relationship with the manager, 4. Relationships with seniors, 5. Relationships with colleagues, 6. Working status/working hours, 7. Long working hours/overwork, 8. Family matters, 9. Job transfer of family member, 10. Marriage, 11. Childbirth/child-rearing, 12. Nursing care for family members, 13. Personal health problem, 14. To improve the level of work content, 15. Inadequate training program, 16. Limits of personal skills, 17. The job was not rewarding, 18. Interest in the different fields, 19. Others(2)What do you think should have been improved about your workplace where you were working last? Select all that apply and mark the best answer separately.1. Improvement of working conditions , 2. Reduction of workload, 3. Interpersonal relationships at the workplace, 4. Reduction of working hours, 5. Taking a vacation, 6. Enhancement of child-rearing support, 7. Enhancement of nursing care support, 8. Evaluation of expertise, qualifications, etc., 9. Enriching opportunities to improve personal skills, through education, training, etc., 10. Introduction of various work styles and working hours, 11. Enhancement of the medical safety system, 12. Ensuring employment stability, 13. Enrichment of employee benefits, 14. Nothing in particular, 15. Other.(3)How long has it been since you left your job as a dental hygienist?(4)Do you want to start working as a dental hygienist again? Select one.1. I want to re-enter as soon as possible, 2. I want to re-enter if conditions are satisfied, 3. I do not intend to, 4. I do not know.(5)Do you want to start working again at the same workplace where you were last working as a dental hygienist? Select one.1. I want to re-enter as soon as possible, 2. I want to re-enter if conditions are satisfied, 3. I do not intend to 4. I do not know.(6)If you were to start working again, how would you find a workplace? Multiple choice.1. Labor agency, 2. Job magazines, 3. Recommendation from a friend/acquaintance, 4. Recommendation from a dental hygienist school, 5. Internet, 6. Free referral by the Dental Association and Dental Hygienist Association, 7. Human resource dispatch companies, 8. Other(7)(1) Are there any obstacles that are making it difficult for you to start working again as a dental hygienist?1. Yes, 2. No(2) What are these obstacles? Multiple choice.1. Salary, 2. Working hours, 3. My skills, 4. No consultation, 5. Aging, 6. Others(8)Where do you want to start working again as a dental hygienist? Multiple choice.1. Clinic, 2. Hospital/university hospital, 3. Clinic for special needs dentistry, 4. Administration, 5. Dental hygienist education and training institution, 6. Clinic attached to the company, 7. Companies/business establishments, 8. Dental health examination/health activity organization, 9. Social welfare facility, 10. Long-term care insurance facilities, etc. (Please mark the relevant facilities with a circle), 11. Regional comprehensive support center, etc., 12. Research institute, 13. Other.(9)What are the areas of your interest? Multiple choice.1. Community health, 2. Home-based dental care , 3. Geriatric dentistry, 4. Special needs dentistry, 5. Occupational dental health, 6. Dental hygienist education and training institution, 7. Nothing in particular, 8. Other.(10)Would you want to participate in a lecture-based course for re-entry?1. Yes, 2. No.(11)What kind of lecture-based courses would you want to attend? Multiple choice and choose the best answer.1. Professional oral care techniques, 2. Scaling and route planning, 3. Dental caries prevention and control, 4. Dental health guidance for individuals, 5. Dental health guidance for group, 6. Handling of dental materials, chairside assistant, 7. Chairside assistant techniques, such as snap impression, polishing of filling materials, rubber dam, etc., 8. Counseling skills, 9. Dysphagia rehabilitation, 10. Myofunctional therapy, 11. Nursing care skills, 12. Other.The questionnaire is available in Japanese from the Japan Dental Hygienists’ Association .Descriptive statistics and cross-tabulations with age groups were summarized for the questions presented above. Chi-square tests were used to find out the statistical significance. A logit model of log-linear analysis was used to identify statistically significant cells. To visualize the relations, a correspondence analysis was conducted. The results are expressed as biplots. SPSS Statistics Ver 24.0  was used for the analysis.Informed written consent was obtained from all participants. This study was approved by the Ethics Committee of the Tsurumi University School of Dental Medicine  and conducted in accordance with the Declaration of Helsinki.The Japan Dental Hygienists’ Association distributed the questionnaires to 16,113 of its members, and 8780 responded (collection rate: 54.5%). Among them, there were 1063 dormant dental hygienists. In this study, the data analysis included 1063 dental hygienists. Their mean age was 52.36 ± 13.06 years. They were all women.The main reasons for leaving a job were “Childbirth/child-rearing” (16.9%) and “Relationship with the manager” (15.7%). Leaving due to “Childbirth/child-rearing” was a statistically significant factor for the age groups younger than 49. For those in their 20s and 40s, “Childbirth/child-rearing” and “Relationship with the manager” were the main reasons for leaving a job. For those in their 30s, “Childbirth/child-rearing” (40.6%) was the most frequent reason for leaving a job. For those in their 50s, the most frequent reason for leaving a job was “Interest in a different field” (18.2%). For those in their 60s, the most frequent reason for leaving a job was “Personal health” (16.4%). For those in their 70s, the most frequent reason for leaving a job was “Family matters” (18.1%).Regarding the item about factors that needed to be improved in the last workplace environment, 285 dental hygienists (28.1%) answered “Interpersonal relationships at the workplace,” which was the most common response, followed by “Improvement of salary ” (25.5%). These answers were statistically significant factors for individuals in all age groups except for those in their 70s. For those aged below 40, the most frequent request was “Interpersonal relationships at the workplace.” For those in their 50s, “Improvement of working conditions ” (28.2%) and “Interpersonal relationships at the workplace” (28.2%) were the most common answers. For those in their 60s, “Improvement of the working conditions ” was the most frequent response. For those in their 70s, “Evaluation of expertise, qualification, etc.,” (19.7%) was the most frequent response.The main obstacle to working again was “Working hours” (58.1%). For respondents in their 20s, “My skills” (75.0%) was a major obstacle. For those in their 30s and 40s, “Working hours” was a major obstacle. For those in their 50s and 60s, “Aging” presented a major obstacle. For those in their 70s, “Working hours” and “Aging” were major obstacles.Approximately 48% of subjects stated that they wish to participate in an educational or upskill workshop to aid in workplace re-entry. “Counseling skills” was the program that attracted the greatest level of interest (70.0%). “Dysphagia rehabilitation” was a highly requested program for all age groups except participants aged in their 20s. For those younger than 39, the “Scaling and route planning” program was frequently of interest. This was a statistically significant answer for respondents in their 20s, 30s, and 40s. For age groups older than 40, “Counseling skills” was frequently of interest.In terms of finding a new workplace, approximately 70% of subjects stated that they would use a “Labor agency.” For all generations, “Labor agency” was the most popular answer to this question. For age groups younger than 30,” the number of subjects who answered “Internet” was notable.A cross-tabulation showing participants’ willingness to re-enter the workforce versus items related to leaving jobs and re-entry is shown in The main reason why dental hygienists who wished to re-enter the workforce had left their jobs was “Childbirth/child-rearing” (17.0%). This reason was statistically significant related to the statement “I want to re-enter if conditions are satisfied.”For the question on improvements that should be made to their last workplace environment, 28.0% of subjects answered: “Interpersonal relationships at the workplace.” This item was statistically significantly related to the response “I want to re-enter if conditions are satisfied.” The response “I want to re-enter as soon as possible” was statistically significantly related to the answers “Interpersonal relationships at workplace,” “Evaluation of expertise, qualifications, etc.,” “Enhancement of medical safety system,” “Ensuring employment stability,” and “Enrichment of employee benefits.”In terms of obstacles to working again, 57.9% of subjects selected “Working hours.” This item was identified as the major obstacle for subjects who answered “I want to reenter if conditions are satisfied.” For the subjects who answered “I want to reenter as soon as possible,” “My skills” was identified as the major obstacle.Many subjects stated that they would be interested in participating in two lecture courses: “Dysphagia rehabilitation” (70.3%) and “Myofunctional therapy” (61.7%). Many of the subjects who answered “I want to re-enter as soon as possible” and “I want to re-enter if conditions are satisfied” selected these two lecture courses.To find a new workplace, 70.1% of subjects stated that they would use a “Labor agency.” The answers “Recommendation from a friend/acquaintance” and “Internet” were statistically significantly related to the response “I want to re-enter as soon as possible.”The cross-tabulation of the items investigated in this study against age groups was illustrated graphically by correspondence analysis. The Japan Dental Hygienists’ Association surveys the working conditions of dental hygienists every five years. In this survey, dental hygienists who had left their jobs were included. A report of this survey was presented on the homepage of the Japan Dental Hygienists’ Association . One of By Japanese dental hygienist law, only women can be licensed dental hygienists. The law was amended in 2015, and since then, men have also been allowed to be licensed as dental hygienists. However, the number of dental hygienists is still at a low level.More than approximately 40% of dental hygienists surveyed stated that they do not wish to reenter the dental hygienist workforce. The social position of dental hygienists needs to improve and should be reflect by salaries that are commensurate with the work involved. On the other hand, around 40% of dormant dental hygienists stated that they would like to re-enter the workforce. Encouraging dormant dental hygienists to re-enter the workforce is an effective strategy to resolve the supply–demand imbalance. Many dental hygienists who stated that they would like to re-enter feel that there are obstacles to re-entry. Therefore, analyzing the reasons for leaving jobs, obstacles to reentry, and ways to improve the working environment is essential, especially to encourage dental hygienists who wish to reenter the workforce immediately.The major reason reported for leaving a job was “Childbirth/child-rearing.” These respondents stated that they would like to re-enter the workforce if conditions are improved. The log-linear analysis indicated that “Childbirth/child-rearing” was a statistically significant factor for the younger generation (those aged less than 49 years old). In addition, this item was statistically significantly related to the response “I want to reenter if conditions are satisfied.” The correspondence analysis revealed that “Childbirth/child-rearing” is the most important factor that needs to be addressed to entice dormant dental hygienists to return to work.“Relationship with the manager” was the second most common reason given for leaving a job. Some dental hygienists stated that they had left jobs due to human relationships with seniors or colleagues. More than half of them wished to re-enter.In terms of improving the working environment, “Improvement of working condition ” and “Interpersonal relationships in the workplace” had high response rates. The log-linear analysis indicated that the item “Improvement of working conditions ” was a statistically significant response for all generations, except for participants in their 70s. Under the Japanese medical insurance system, each dental practice gives fixed pay. Japanese dental hygienist law regulates the practice of dental hygienists, requiring the instruction of a dentist. The salary of a dental hygienist depends on the interests of the dental office . FurtherWhen focused on respondents in their 30s, “Enhancement of child-rearing support” and “Introduction of various work style and working hours” were shown to be statistically significant factors. Considering that a frequent reason for leaving a job was “Child-birth/child-rearing,” flexible work arrangements are needed. Unfortunately, most dental clinics in Japan operate on a small scale and are privately managed. The number of dental hygienists is not sufficient. It is currently hard to introduce a flexible working system. Therefore, a social support system is necessary to resolve this issue. The Japanese government has been developing policy measures to improve the working environment for women. Several points need to be improved, including working hours. These factors are not unique to Japan. Similar problems occur in other parts of the world ,15,16.Frequent obstacles to re-entry were “Working hours,” “My skills,” and “salary.” For respondents under the age of 50, more than 70% of dental hygienists recognized working hours as being an obstacle. This result has been found in previous studies in Japan ,14,15,16“My skills” was also cited as a frequent obstacle. For respondents in their 20s, 75% recognized their skills as being an obstacle. For respondents in their 60s, 32.4% recognized skills as being an obstacle. Moreover, for the subjects who answered “I want to reenter as soon as possible,” “My skills” was a statistically significant response. Many of the subjects stated that they would like to participate in a lecture-based course for reentry. Many of the subjects who answered “I want to re-enter as soon as possible” and “I want to re-enter if conditions are satisfied” selected two lecture courses as being of interest: “Dysphagia rehabilitation” and “Myofunctional therapy.” The results showed a different tendency to previous surveys ,18. In pMore than 40% of the subjects stated that they would be interested in courses on scaling root plaining and professional oral care techniques. More than 77% of subjects in their 20s and more than half of those in their 40s gave this response. Dental hygienists may recognize these fundamental skills as being a must for working as dental professionals. On the contrary, “limits of personal skills” was not stated as a major reason for leaving a job. Removing anxiety related to skills may promote re-entry. Further improvement of the skill-up system is necessary. Respondents in the younger age group (≤29) stated that they would be interested in receiving a lecture on “Enriching opportunities to improve personal skills, through education, training, etc.” Most dental hygienist schools in Japan involve a 3-year diploma program. In most cases, working as a dental hygienist involves long working hours. There are limited opportunities to participate in postgraduate education or training programs.There are several limitations to this study. First, the study population was limited to the members of the Japan Dental Hygienists Association. Second, the data were collected from individuals who self-enrolled in the study. Third, the data were self-reported, and the subjects’ actual behaviors were not observed. In addition, not all subjects answered all of the questions.Dental clinics in Japan are experiencing a shortage of dental hygienists. Reintroducing dormant dental hygienists into the workforce would be an effective strategy to resolve the supply–demand imbalance. For the re-entry of dormant dental hygienists, the working environment needs to be improved. The introduction of a flexible working system and training programs focused on re-entry as well as the improvement of human relationships may be key factors.