This cross-sectional study examined the actor and partner effects of beliefs about AIDS-related death on quality of life in Chinese married couples in which both were living with HIV.A total of 49 married couples in central China who were both infected with HIV completed measures to assess their beliefs about AIDS-related death and quality of life.r = .40) and quality of life–mental health summary (r = .31), respectively, within the couple. Both actor and partner effects of beliefs about AIDS-related death on the quality of life–mental health summary, rather than the quality of life–physical health summary, were significant within the husband-wife dyad.In the actor-partner interdependence model, the husband-wife dyad showed congruence in their beliefs about AIDS-related death (Our findings indicate the dyadic interdependence of beliefs about AIDS-related death and the quality of life–mental health summary in married couples. Psychosocial interventions that target a reduction of negative death beliefs and enhancement of well-being in the context of HIV should treat the couple as a unit. Due to pessimism about the prognosis of HIV and the wide stigma attached to this disease, people with HIV tend to present negative beliefs about death. This is particularly significant among people who were accidentally infected with HIV while giving a commercial blood donation to ease their financial strain  and are Living with HIV can be torturous, and dying of AIDS may also be attached with tremendous suffering. Dying AIDS patients have been described in extremely negative ways, such as, “When they get sick it’s really scary. Their skin and face become white and start to peel off layer by layer,” and “She couldn’t eat anything. She became so thin that it was frightening” . MisundeHusband and wife are both affected by chronic illness because the disease has a wide impact on a couple . The famaH) and 2) the wife’s beliefs about AIDS-related death on her own QoL (aW). In addition, the partner effects examined are: 1) the husband’s beliefs about death on his wife’s QoL (pW), and 2) the wife’s beliefs about death on her husband’s QoL (pH)   has beenBy examining dyadic interdependence in a sample of Chinese married couples who are both infected with HIV, we hypothesized that 1) the husband-wife dyad will show significant congruence in their beliefs about AIDS-related death and QoL, respectively; and 2) significant actor and partner effects of beliefs about AIDS-related death on QoL will be seen within the husband-wife dyad  test of model fit, 2) the root mean square error of approximation (RMSEA), 3) the comparative fit index (CFI), 4) the Tucker-Lewis index (TLI), and 5) the standardized root mean square residual (SRMR). A good fit is demonstrated with an RMSEA value of less than .06, CFI of .95 or above, TLI of .90 or higher, and SRMR value below .08 [p values of less than .05 were considered to indicate statistical significance. According to Cohen’s guidelines to interpret effect size [The couples’ demographic and HIV-related characteristics were tabulated. The Pearson correlations were used to test for bivariate associations between beliefs about AIDS-related death and the two dimensions of the QoL measure among the couples. The APIM approach  was applelow .08 . We condect size , .10 is Table r = .40, p < .01) and their QoL–mental health summary , but not in their QoL–physical health summary . Although not significantly associated with the QoL–physical health summary , the husbands’ beliefs about AIDS-related death was negatively associated with their QoL–mental health summary . The wives showed a similar pattern in which their beliefs about AIDS-related death were not significantly associated with their QoL–physical health summary , but were negatively associated with their QoL–mental health summary . Therefore, we excluded the results of the QoL–physical health summary from further analysis with the APIM.In Table 2 [p = .30; RMSEA = .04; CFI = .99; TLI = .98; SRMR = .06) [In APIM analysis using Mplus 7, the model fit the data well  . All actFocusing on a dyadic perspective, this study provides new information about the interdependence of Chinese married couples who are both infected with HIV. The results show that 1) both members of the husband-wife dyad reported a moderate level of congruence in their beliefs about AIDS-related death and their score on the QoL–mental health summary, respectively; and 2) the husbands’ beliefs about AIDS-related death affected not only their own QoL–mental health summary but also those of their wives, and vice versa.As expected, the couples shared beliefs about AIDS-related death, indicating that they present a similar cognitive scheme regarding the HIV prognosis and finality. In addition, the couples showed congruent QoL, particularly in the mental health summary, which is consistent with the results of previous dyadic studies on chronic illness , 22. ThiNotably, significant actor and partner effects were shown in the effects of beliefs about AIDS-related death on the QoL–mental health summary in the married couples. Because both husbands and their wives were infected with HIV, the actor and partner effects are comparable in strength, unlike the dyad of patients and caregivers, which shows higher actor effects than partner effects . These nThis study used a small convenience sample, which is not representative of the couples infected with HIV. We did not calculate the statistical power before this pilot study because couples with both members infected with HIV were difficult to recruit. In addition, the moderate response rate suggests that there may be a bias in recruitment and that the results should thus be interpreted with caution. The cross-sectional design of this study does not inform directions of effects; for example, a couple’s poor quality of life might drive their negative beliefs about death. Longitudinal studies are needed to examine the prospective effects of the key variables in the husband-wife dyad. In addition, this study relied on self-reporting, and future studies may consider the use of physiological or other objective indicators to observe the dyadic interdependence.Despite these limitations, by indicating the actor and partner effects of beliefs about AIDS-related death on QoL within married couples who are both infected with HIV, this study contributes to the growing knowledge about dyadic interdependence in the context of HIV. The mutual influences in the dyadic relationships affected by HIV require further investigation. In addition, these findings have public health implications in the design of couple-based intervention programs for HIV prevention and treatment.


The single cell RNA sequencing (scRNA-seq) technique begin a new era by allowing the observation of gene expression at the single cell level. However, there is also a large amount of technical and biological noise. Because of the low number of RNA transcriptomes and the stochastic nature of the gene expression pattern, there is a high chance of missing nonzero entries as zero, which are called dropout events.We develop DrImpute to impute dropout events in scRNA-seq data. We show that DrImpute has significantly better performance on the separation of the dropout zeros from true zeros than existing imputation algorithms. We also demonstrate that DrImpute can significantly improve the performance of existing tools for clustering, visualization and lineage reconstruction of nine published scRNA-seq datasets.https://github.com/gongx030/DrImpute.DrImpute can serve as a very useful addition to the currently existing statistical tools for single cell RNA-seq analysis. DrImpute is implemented in R and is available at The online version of this article (10.1186/s12859-018-2226-y) contains supplementary material, which is available to authorized users. DNA sequencing technology and next generation sequencing approaches for high-throughput RNA sequencing are experiencing tremendous growth. Bulk RNA sequencing (bulk RNA-seq) technology performs high throughput sequencing of RNA isolated from millions of cells, which implies that the resulting expression value for each gene is the average expression value of a large population of input cells , 2. Thustrue zeros, where the genes are not expressed at all, and the dropout zeros are due to the so-called dropout events [However, scRNA-seq has a relatively higher noise level than bulk RNA-seq especially due to so-called dropout events –14. The t events . Dropoutt events . We hypomean imputation estimates missing entries by averaging gene-level or cell-level expression levels [hot deck imputation predicts missing values from similar entries using a similarity metric among genes  are also challenged from a missing value problem . Variousn levels –19; (2) NNImpute ); (3) moMCimpute ); (4) muEQimpute ); and . For each combination of distance metric (Spearman or Pearson) and k, we estimated the zero values in the input gene-cell matrix. The averaged estimation over all combinations were taken as the final imputed values  of the total number of reads, mapped the sampled reads onto the genome and computed the corresponding gene-cell read count matrices. We defined dropout zero as the genes where expression levels were zero in the down-sampled datasets, but were positive in the full dataset.We first investigated the performance of DrImpute on discriminating true zeros and dropout zeros in the scRNA-seq data matrix using a down-sampling based simulation method. We defined the Then, we utilized DrImpute, along with two other published scRNA-seq imputation tools scImpute and MAGIC to impute zero events in the down-sampled dataset. The imputed zero events could therefore be grouped into four situations: (1) true positive , (2) true negative , (3) false positive  and (4) false negative . The F1 score  was used to evaluate the imputation performance of each method on down-sampled datasets. We found that DrImpute had consistently better performance of discriminating the true zeros and the dropout zeros at various down-sampling ratio on both Pollen and Usoskin datasets Fig.  and c.Discovering distinct cell types from a heterogeneous cell population (cell clustering) is one of the most important applications of scRNA-seq. Several methods, such as pcaReduce , SC3 2626, and tFirst, we evaluated whether imputing the dropout events using DrImpute before applying pcaReduce, SC3, and t-SNE would improve the accuracy of cell type identification. We compared the clustering performance of these methods with and without imputing dropout events by DrImpute, on seven published scRNA-seq datasets. Using the cell types reported in the original publications as the ground truth and the Adjusted Rand Index (ARI) as the performance metric, we observed that preprocessing the scRNA-seq datasets with DrImpute significantly improved the clustering performance of pcaReduce with the M and S options  on all seven tested datasets; improved the performance of t-SNE followed by k-means (t-SNE/kms) on five datasets; and improved the performance of SC3 on three datasets Fig. . Second,Figure We further assessed whether preprocessing scRNA-seq by imputing dropout events would produce more consistent clustering results. We evaluated the robustness of the clustering results with and without imputing the dropout events using DrImpute. We hypothesized that preprocessing the scRNA-seq with DrImpute would facilitate the clustering methods to detect more robust and consistent subpopulations. For each dataset, we randomly sampled 100 genes (gene level down-sampling), or one-third of the total cells (cell level down-sampling), and we clustered the cells using each of the clustering methods with and without preprocessing the down-sampled dataset using DrImpute. This process was repeated 100 times, and we compared how consistent the clustering results were after down-sampling the genes or cells as measured by cross ARI see . For botIn summary, these results suggested that in 55 out of 66 (83%) tested cases, preprocessing the scRNA-seq datasets by imputing the dropout events using DrImpute significantly improved the accuracy or the robustness of clustering methods that did not specifically address dropout events. Compared with other scRNA-seq imputation tools such as scImpute, CIDR and MAGIC, DrImpute combined with t-SNE/kms had improved clustering performance on 16 of 21 (76.2%) tested cases.Principal component analysis (PCA) and t-SNE are among the most popular methods for visualizing scRNA-seq in a two- (2D) or three-dimensional (3D) space. However, neither PCA nor t-SNE explicitly addressed dropout events. Zero Inflated Factor Analysis (ZIFA) was the first specific tool designed for factorizing and visualizing scRNA-seq data , followeTo evaluate the accuracy of the dimension reduction in 2D space, we first estimated how discriminatively the cells from one population  separated from other populations in 2D space. For each dimension reduction result, we used the 2D coordinates of 90% of cells as the feature to train a linear support vector machine (SVM) classifier, and we predicted the class label for the remaining 10% of the cells. The above process was repeated ten times, and the overall prediction accuracy  was used to quantitatively measure the separation of different populations in 2D space.We compared the performance of PCA and t-SNE with and without DrImpute preprocessing as well as ZIFA and t-SNE with scImpute on seven published scRNA-seq datasets. We observed significant improvements in PCA or t-SNE with DrImpute on 9 of 14 (64.3%) tested cases Fig. . MoreoveFigure In summary, we found that preprocessing the scRNA-seq datasets by imputing the dropout events using DrImpute significantly improved the accuracy of visualization. The generic dimension reduction methods (PCA and t-SNE) on imputed datasets using DrImpute also performed significantly better than ZIFA, which was specifically designed for scRNA-seq data considering dropout events.The third common task for single cell RNA-seq analysis is to reconstruct the lineage trajectories and infer the differentiated and progenitor states of the single cells. For example, Monocle  and TSCAWe compared the performance of pseudotime inference with and without imputing the dropout events on three published temporal scRNA-seq datasets, mouse preimplantation embryonic development data (Deng ), human We found that both Monocle and TSCAN had significantly improved performance on pseudotime inference on all three tested datasets if the scRNA-seq data were preprocessed by DrImpute, as supported by the significant increase of both POS and Kendall’s rank correlation score Fig. . Figure As another example, Fig. In summary, these results suggested that imputing dropout events using DrImpute also improved the performance of pseudotime inference using Monocle and TSCAN.Dropout events and large cell-level variability are characteristic of scRNA-seq data, which are different from bulk RNA-seq data. However, many statistical tools derived for scRNA-seq data in cell type identification, visualization, and lineage reconstruction did not model for dropout events. Thus, we proposed a method for imputing dropout events considering cell-level correlation and systematically compared the performance without and with the imputation of dropout events. Our results on nine scRNA-seq datasets showed that imputing the dropout events using DrImpute significantly improved the performance of existing tools on cell type identification, visualization, and lineage reconstruction.We would like to emphasize that DrImpute is the very first algorithm that sequentially utilizes dropout imputation with existing tools for more effective analysis. There are some statistical tools that model dropout events for specific purposes, such as BISCUIT, ZIFA, CIDR, scImpute and MAGIC. However, none of these suggest and compare the sequential use of dropout imputation and existing methods. We developed DrImpute to impute dropout events and demonstrated that the sequential use of dropout imputation employing DrImpute followed by the use of existing tools greatly improved the performance of the existing tools.One of the limitations of DrImpute is that it considers only cell-level correlation using a simple hot deck approach. The gene-level correlation also exists, and more sophisticated modeling would improve the performance of the imputation. Most missing value imputation methods in bulk RNA-seq utilize gene-level correlation to impute missing values; for example, LLSimpute uses a local gene-level correlation structure to build local linear regression models to estimate missing values . One mayThe main goal of the current study was to de-noise the biological noise in scRNA-seq data by imputing dropout events. We developed DrImpute and proposed the sequential use of DrImpute on existing tools that do not address dropout events. The results suggested that DrImpute greatly improved many existing statistical tools  that do not address the dropout events in three popular research areas in scRNA-seq—cell clustering, visualization, and lineage reconstruction. In addition, DrImpute combined with pcaReduce, SC3 or t-SNE/kms showed higher performance in cell clustering than CIDR, which was specifically designed for the cell clustering of scRNA-seq data. DrImpute combined with PCA or t-SNE also demonstrated higher performance in 2D visualization than did ZIFA, which was specifically designed for the dimensional reduction of scRNA-seq data considering dropout events. Moreover, DrImpute imputed dropout events better than scImpute and MAGIC, as we have shown that the performance of t-SNE increased greatly in regard to cell clustering and visualization with DrImpute compared to that with scImpute. In summary, DrImpute can serve as a very useful addition to the currently existing statistical tools for single cell RNA-seq analysis.log10(X + 1)). Table Seven scRNA-seq datasets  were used for cell clustering and visualization. Three temporal scRNA-seq datasets  were used for lineage reconstruction. Genes that were expressed in fewer than 2 cells were removed. The raw read counts were normalized by size factor , followeX be a n by p log transformed gene expression matrix, where n is the number of rows (genes) and p is the number of columns (cells). The th component of X is represented as xij. Let H be the number of clustering configurations (e.g. combinations of distance metric and number of clusters), and C1, C2, …, Ch are each clustering results. Given that the clustering of Ch is a true hidden cell classification, the expected value of a dropout event can be obtained by averaging the entries in the given cell cluster:Specifically, let E(xij| Ch) = mean(xij ∣ xij are in the same cell group in clustering Ch).E(xij| Ch) was computed for each clustering result C1, C2, …, CH, and the final imputation for the putative dropout events xij, and E(xij), was computed as a simple averaging:This step was also schematized in Additional file C1, C2, …, CH, we used an approach similar to that of SC3. We first created a similarity matrix among cells using Pearson and Spearman correlations. K-means clustering was performed on the first 5% of the principal components of the similarity matrix and the number of clusters ranged from 10 to 15. Thus, the default setting had a total of 12 clustering results  times six numbers of clusters (10 to 15) for k-means clustering). This default setting was used for all the data analysis in this manuscript except for the down-sampling cells for the Blakeley dataset, which only had 30 cells. Its sample size was too low to use a default range for the number of clusters, so in this case, we used a clustering group size of 6 to 10.For the default clustering of k = 10 − 15 (default), k = 10 − 20, k = 10 − 25 and k = 10 − 30, as well as different random number seeds for k-means initialization. The robustness was quantitatively measured as Pearson’s correlation coefficient of imputed zero entries between any two conditions (choices of k ranges and random seeds). We found that on two tested datasets (Pollen and Usoskin), the imputed results were generally robust on different choices of k ranges and random seeds  [k may be necessary to obtain most accurate imputation results.Moreover, our experience with DrImpute suggested that the range of ecified) , 25, 48.In order for DrImpute efficiently imputing large-scale scRNA-seq datasets, we have improved the running efficiency in two ways. First, for large scRNA-seq datasets, we adopted a sampling-based algorithm without computing the full cell-cell distance matrices . Second,https://github.com/JustinaZ/pcaReduce). We performed the analysis using the S and M options with the default setting.The pcaReduce software was downloaded from the authors’ GitHub (http://bioconductor.org/packages/release/bioc/html/SC3.html). To ensure the consistency of the comparison with other tools, the gene filtering option was turned off (gene.filter = FALSE). Other options were set as default.The SC3 package was downloaded from R Bioconductor (The Rtsne package and kmeans function in R program were used for t-SNE (perplexity = 9) followed by k-means. The log transformed expression data were centered as the gene level. We used the R kmeans function with the option iter.max = 1e + 09 and nstart = 1000 for stable results.https://github.com/epierson9/ZIFA). We used block_ZIFA with k = 15 for all data analysis, and we used the first two dimensions for visualization and evaluation.ZIFA software was then downloaded (https://bioconductor.org/packages/release/bioc/html/monocle.html). In Monocle analysis, we first selected genes expressed in at least 50 cells and then selected differentially expressed genes using the differentialGeneTest function . If there were no differentially expressed genes using the provided test, all genes expressing at least 50 cells were used for the subsequent analysis.Monocle was downloaded from the R Bioconductor page (https://www.bioconductor.org/packages/release/bioc/html/TSCAN.html). All default settings were used for TSCAN.TSCAN was downloaded from the R Bioconductor page (https://github.com/KrishnaswamyLab/magic), and the R version of MAGIC was used for the analysis. As suggested in their manual page, we used settings t = 6 and rescale_percent = 0.99.The MAGIC package was downloaded from GitHub (https://github.com/Vivianstats/scImpute). We used the settings drop_three = 0.5 and four CPU cores for the analysis. The Kcluster parameter was set as the expected number of cell clusters in each dataset (e.g. Kcluster = 11 for Pollen dataset).The scImpute package was downloaded from GitHub


Nearly half of patients with perihilar cholangiocarcinoma (PHC) have incurable tumors at laparotomy. Staging laparoscopy (SL) potentially detects metastases or locally advanced disease, thereby avoiding unnecessary laparotomy. However, the diagnostic yield of SL has decreased with improved imaging in recent years.The aim of this study was to identify predictors for detecting metastasized or locally advanced PHC at SL and to develop a risk score to select patients who may benefit most from this procedure.Data of patients with potentially resectable PHC who underwent SL between 2000 and 2015 in our center were retrospectively analyzed. Multivariable logistic regression analysis was used to identify independent predictors and to develop a preoperative risk score.N = 203 patients), intermediate-risk of 21 % (N = 39), and high-risk of 58 % (N = 31).Unresectable PHC was detected in 41 of 273 patients undergoing SL (yield 15 %). Overall sensitivity of SL was 30 %, with highest sensitivity for detecting peritoneal metastases (73 %). Preoperative imaging factors that were independently associated with unresectability at SL were tumor size ≥4.5 cm, bilateral portal vein involvement, suspected lymph node metastases, and suspected (extra)hepatic metastases on imaging without the possibility of diagnosis by percutaneous- or endoscopic ultrasound-guided biopsy. The derived preoperative risk score showed good discrimination to predict unresectability  and identified three subgroups with a predicted low-risk of 7 %  contains supplementary material, which is available to authorized users. Perihilar cholangiocarcinoma (PHC) is a rare disease with a dismal prognosis for which radical resection remains the only curative treatment.As the routine use of SL in PHC patients does not seem justified, a selective approach to identify patients who may benefit most from this procedure seems warranted.Consecutive patients with suspected PHCAll patients and radiological scans were discussed in a multidisciplinary, hepatopancreatobiliary (HPB) team meeting. In the event of suspected distant lymph node or organ metastases, percutaneous- or endoscopic ultrasound (EUS)-guided biopsy was attempted in order to confirm metastatic disease. When tumors were considered potentially resectable, SL was planned early in the preoperative workup in all patients with Bismuth–Corlette (BC) type 3–4 tumors. Laparoscopy for BC type 1–2 tumors was conducted more selectively according to the surgeon’s preference. Laparoscopy was also performed in the event of suspicious metastatic lesions on imaging for which diagnosis by percutaneous- or EUS-guided biopsy was not feasible or when pathological results of biopsies were inconclusive with persistent suspicion of metastatic disease.SL was carried out by the HPB surgical fellow or surgeon and included inspection of the liver and gallbladder surface, peritoneal cavity, and hepatoduodenal ligament.Patients were scheduled for exploratory laparotomy when no metastases or locally advanced tumors were found at SL, when any new imaging did not show disease progression, and if the patient remained fit to undergo surgery. At laparotomy, the abdomen was inspected for any signs of incurable disease, such as peritoneal deposits, liver metastases, lymph node involvement beyond the hepatoduodenal ligament (N2), or locally advanced disease. Tumors were considered locally advanced if they invaded surrounding organs or when excessive vascular or biliary involvement precluded an R0 or R1 resection and only R2 resection was possible. Portal vein reconstructions were performed if necessary and technically feasible. All suspicious lesions and lymph nodes were biopsied and analyzed by frozen-section microscopic examination.Study variables included clinical variables  and radiological parameters that were retrospectively rereviewed on available computed tomography (CT) and magnetic resonance imaging (MRI) scans by an experienced staff radiologist (CYN) who was blinded to the outcome of SL.Radiological parameters included BC classification, tumor size, vascular involvement, lobar atrophy, suspected lymph node metastases, and other suspicious metastatic lesions . Suspicious lymph nodes were larger than 10 mm in short-axis diameter, had irregular border, or showed central necrosis and were categorized as perihilar (N1) or beyond the hepatoduodenal ligament (N2).The diagnostic accuracy of SL was expressed as the yield and sensitivity to detect incurable disease. The yield and sensitivity were calculated by dividing the total number of avoided laparotomies by the total number of laparoscopies and all patients with unresectable disease, respectively.p value < 0.100 in univariable analysis were subsequently entered in multivariable analysis. A cut-off for tumor size was used in these analyses and determined at the highest sensitivity and specificity. A standard approach was then used to develop a risk score.p < 0.05 in multivariable analysis) were selected and regression coefficients of these predictors were transformed into simple points to develop the risk score. The number of points assigned to each predictor equaled its regression coefficient in multivariable analysis divided by the predictor with the smallest absolute number of points, and rounded to the nearest whole number. Predicted risks were then calculated for each patient in the study cohort by applying total point scores to the logistic regression formula. Risk score tertiles were used to categorize patients into low-risk, intermediate-risk, and high-risk groups based on the predicted chance of finding metastases or locally advanced disease at SL.Logistic regression analysis was used to identify predictors of unresectable disease at SL. All study variables with a p < 0.05) indicating a lack of fit. Missing data were rare and were handled with complete case analysis. All analyses were performed using IBM SPSS Statistics version 22.0  and R Version 3.1.2 .Predictive accuracy (discrimination) of the risk score was assessed using area under the curve (AUC) analysis with 95 % confidence intervals (CIs). The agreement between predicted and observed unresectability  was assessed using the Hosmer–Lemeshow goodness-of-fit test, with a significant outcome . Lesions that were mainly detected were peritoneal and liver metastases. Twenty-nine patients who were considered resectable at SL did not undergo laparotomy , pneumonia (N = 1), pain requiring prolonged hospital stay (N = 1), PTC drain dislocation (N = 1), and fever requiring antibiotics (N = 2). Complications after exploratory laparotomy occurred in 27 patients (33 %) with unresectable disease, and included 10 major complications (including one death). Median hospital stay for SL was 3 days (range 1–9), including the day of admission.Complications after SL occurred in eight patients (3 %) and were all minor (Clavien–Dindo grade I–II) and included urinary retention  that were identified were tumor size (≥4.5 cm), portal vein involvement , suspected metastases in N2 lymph nodes, and suspected (extra)hepatic metastases. No association was found for proximal extent of bile duct involvement (BC classification).Univariable and multivariable analysis of predictors for detecting metastasized or locally advanced PHC at SL are shown in Table There was no difference in the yield of SL in patients who underwent MRI  compared with those who did not undergo MRI .N = 203 patients), 21.3 % in the intermediate-risk tertile , and 58.0 % (range 48.5–91.9 %) in the high-risk tertile .The derived preoperative risk score to predict detection of metastasized or locally advanced PHC at SL is presented in Table p = 0.995). Predictive accuracy remained good after categorizing patients into low-risk, intermediate-risk, and high-risk groups .Predictive performance of the preoperative risk score was well, with an AUC of 0.77 (95 % CI 0.68–0.86) and excellent calibration was observed  and overall sensitivity (30 %) of SL were found to detect unresectable PHC. Several independent risk factors were identified that accurately predicted detection of metastases or locally advanced tumors. A preoperative risk score was developed that showed good discrimination to predict unresectable PHC at SL.Few reports have studied the additional role of laparoscopy in preoperative staging of PHC, with varying results.In this study, SL had the highest sensitivity for detecting peritoneal metastases, whereas sensitivity for liver metastases, locally advanced tumors, and lymph node metastases was poor. A higher incidence of peritoneal and liver metastases was noted in large tumors and tumors with bilateral PV involvement compared with those without these criteria. In addition, among patients in whom N2 lymph node metastases were suspected on preoperative imaging, a substantial proportion had peritoneal metastases at SL. The reasons for missed superficial liver metastases in this study are not entirely clear as most lesions at laparotomy were located in the anterior liver segments and therefore could have potentially been detected at SL.The median interval between SL and laparotomy was 41 days and included required time for adequate biliary drainage and/or hypertrophy to occur after portal vein embolization. Metastases may have developed or may have grown substantially to become visible in that time, although PHC is characterized by a rather indolent growth. Ideally, SL and laparotomy would be performed in a single session in order to limit hospital admissions and surgical procedures. However, diagnosis of malignancy is sometimes difficult on frozen sections and biopsy material may require additional  staining. In addition, many centers face logistical issues related to anesthetic and operating room time planning, and prefer to perform SL separately from laparotomy. Furthermore, early detection of inoperability allows the timely start of palliative care.At laparotomy, N2 lymph node metastases were a common finding precluding resection, of which the majority were located along the course of the common hepatic artery. As others confirm the high incidence of unexpected lymph node metastases at laparotomy,LUS was only performed in four patients in this study period as it was previously found to be of limited value in our center.The eventual yield of SL is influenced by the extent of preoperative imaging. In our cohort, most patients underwent CT, whereas MRI and PET–CT were only performed in selected patients. Limited data are available to assume that the additional use of MRI will increase the yield of imaging in potentially resectable PHC. Previous studies have found no differences in the diagnostic accuracy of CT or MRI for detecting lymph node metastases.The present study has several limitations. The relatively few unresectable tumors that were detected at SL consequently provided a low number of events for statistical analysis, which may have led to statistical uncertainty in the multivariable analysis, as reflected by the relatively wide CIs. Second, we were unable to perform external validation of the proposed risk score because of the limited sample size. Future studies that validate the risk score are therefore desirable. Third, as this study comprises a cohort of 15 years, the quality of preoperative imaging varied during the study period and may have subsequently influenced the assessment of vascular involvement or metastases in the early years. However, scans were rereviewed by a specialized radiologist and we also did not note any changes in the diagnostic yield of SL within the study period.The results from this study support a selective approach to SL in patients with potentially resectable PHC. The proposed preoperative risk score can be useful in selecting patients who may benefit most from this additional staging procedure. Patients in the low-risk group can proceed to exploratory laparotomy without SL. The use of SL in the intermediate-risk group is debatable, whereas patients in the high-risk group are likely to be diagnosed with incurable disease at SL, thereby avoiding an unnecessary laparotomy.Supplementary material 1 (DOCX 15 kb)Below is the link to the electronic supplementary material.


Five out of the 14 IgG4 antigens were validated as class I, five as class II, and four as class III. Antibodies of other IgG subclasses or immunoglobulin classes were present in several diseases and could contribute additional pathogenic mechanisms.IgG4 autoimmune diseases are characterized by the presence of antigen-specific autoantibodies of the IgG4 subclass and contain well-characterized diseases such as muscle-specific kinase myasthenia gravis, pemphigus, and thrombotic thrombocytopenic purpura. In recent years, several new diseases were identified, and by now 14 antigens targeted by IgG4 autoantibodies have been described. The IgG4 subclass is considered immunologically inert and functionally monovalent due to structural differences compared to other IgG subclasses. IgG4 usually arises after chronic exposure to antigen and competes with other antibody species, thus “blocking” their pathogenic effector mechanisms. Accordingly, in the context of IgG4 autoimmunity, the pathogenicity of IgG4 is associated with blocking of enzymatic activity or protein–protein interactions of the target antigen. Pathogenicity of IgG4 autoantibodies has not yet been systematically analyzed in IgG4 autoimmune diseases. Here, we establish a modified classification system based on Witebsky’s postulates to determine IgG4 pathogenicity in IgG4 autoimmune diseases, review characteristics and pathogenic mechanisms of IgG4 in these disorders, and also investigate the contribution of other antibody entities to pathophysiology by additional mechanisms. As a result, three classes of IgG4 autoimmune diseases emerge: class I where IgG4 pathogenicity is validated by the use of subclass-specific autoantibodies in animal models and/or  With the exception of the latter, these mechanisms rely on antibody class and subclass, particularly on the sequence and structure of the constant regions. Single amino acids in the constant region of IgG4 are responsible for structural differences that render it unable to exert most of the known pathogenic functions of antibodies. Despite their immunological inertness, several well-described autoimmune diseases are caused by IgG4 subclass autoantibodies, such as pemphigus, muscle-specific kinase (MuSK) myasthenia gravis (MG), and thrombotic thrombocytopenic purpura (TTP), and in recent years the number of potential IgG4 autoimmune diseases has rapidly grown. By now, 14 autoantigens are known that are targeted by IgG4 subclass autoantibodies; these antigens are found throughout the body (Table Autoantibodies are key pathogenic players in a wide range of autoimmune diseases. Immunoglobulins (Ig) of IgG or IgM class that bind either to cell surface-expressed or extracellular matrix antigens induce organ-specific damage in type II hypersensitivity diseases. More systemic autoimmune diseases are classified as type III hypersensitivity diseases and are characterized by circulating IgG and IgM as well as IgA that binds soluble antigen and forms immune complexes. Antibody-mediated autoimmune diseases include many different pathogenic mechanisms [reviewed in detail by Ref. ]. Among IgG is the predominant antibody class and one of the most abundant glycoproteins in the human plasma with concentrations of approximately 7–15 g/L. In humans, four subclasses are known, IgG1, 2, 3 and 4, which are named in descending order of frequency . IgG4 isH) that mediate the antibody effector functions, a hinge region between CH1 and CH2, and one N-terminal variable domain (VH), which recognizes antigen. Similarly, the light chain is comprised of one variable (VL) antigen binding and one constant (CL) region. The VH contains three complementarity-determining regions (CDR 1–3). These three CDRs, and particularly the CDR3, are hypervariable to allow for improved and highly specific binding of antigen. Increased mutation rates at this genetic locus indicate antigen-driven somatic mutations.The four human IgG subclasses share a similar structure with over 90% sequence homology. IgGs are heterotetramers, consisting of two heavy (50 kDa) and two light chains (25 kDa) of either κ or λ type. The heavy chain consists of three constant domains (C2L2). The heavy chains are mainly connected by disulfide bridges in the hinge region, which vary in numbers between the IgG subclasses. IgG1 and IgG4 have two disulfide bridges in the hinge region, while IgG2 has four and IgG3 11 , and two HL are joined together by covalent and non-covalent interactions between the heavy chains to form a whole antibody , consisting of the CH1, VH, CL, and VL. The corresponding regions in the intact antibody are thus named “Fab” or “Fc” region . As a c (R409K) , 168–170in vivo with endogenous IgG4  at concentrations of 1 mM and less  or on the whole organ by recruitment and activation of complement or immune cells that attack the tissue , 215. An(A)Autoantibodies with specificity for an extracellular antigen are present in the affected organ.in vitro.A pathogenic mechanism for antibodies is demonstrated The autoimmune disease can be reproduced in experimental animals by passive transfer of patient serum or purified abs or active immunization with antigen.Clinical cues for autoimmunity are present such as HLA association, genetic clustering of other autoimmune diseases in the family, and the clinical improvement of the patients after therapies that reduce autoantibody levels, such as plasma exchange or B-cell depletion therapy.Indicators for antibody-mediated autoimmunity(B)Autoantibodies of IgG4 subclass against extracellular antigen are present.in vitro. IgG4 could be purified from patient serum, and the purity of isolated IgG4 should be validated; ideally also the IgG4-depleted IgG1–3 fraction should be used as a control group to ensure the effects derived from IgG4. Alternatively, cloned patient antibodies from IgG4+ B-cells could be used, although these may not be representative of the whole autoimmune B-cell population.A pathogenic mechanism for IgG4 can be demonstrated Reproduction of disease in animals by passive transfer of purified IgG4 from patients, monoclonal IgG or single chain variable region fragments (scFv) cloned from IgG4+ B-cells of patients.Specific indicators for IgG4 pathogenicitySeveral aspects should be considered to define IgG4 autoimmunity:Class I diseases fulfill two or three postulates of IgG4 pathogenicity (B.1–3), here the pathogenicity of IgG4 autoantibodies could be proven by passive transfer of patient IgG4, or an IgG4 pathogenic mechanism was demonstrated in vitro (in most cases this is was a blocking effect). Class II diseases fulfill one postulate for IgG4 pathogenicity (B.1), but there exists substantial circumstantial evidence that would be in line with pathogenicity of IgG4. Examples would be if IgG4 levels correlated with disease severity or the presence of a known pathogenic mechanism that relies on functional blocking. Class III diseases still fulfill one postulate of IgG4 pathogenicity (B.1) but have the least supportive evidence for IgG4 pathogenicity, either because the pathogenic mechanism relies on divalent binding or is unknown. At this point, a conclusion regarding IgG4 pathogenicity cannot be drawn for class II and III diseases, and more studies are required to validate pathogenicity of their IgG4 autoantibodies.The 14 proposed IgG4 autoantibodies and their associated diseases were evaluated according to these aspects . The antigenic targets define different subforms of disease. In pemphigus foliaceus, the antigenic target is desmoglein 1 (Dsg1), which is expressed at high concentrations in the superficial layers of the epidermis; in pemphigus vulgaris, the mucosal-dominant type antibodies target desmoglein 3 (Dsg3) in basal and parabasal layers of the skin. Patients with pemphigus vulgaris of the mucocutaneous type have antibodies against both Dsg1 and Dsg3 , 39. Antinocytes , 219 andinocytes . Additioinocytes , 43. Thiinocytes . Neverthinocytes . The rolinocytes ]. Materninocytes . Antibodinocytes , 222–228inocytes , which cinocytes .in vitro with purified IgG4  is a protease in the blood circulation that cleaves von Willebrand factor (vWF). In TTP, antibodies against the spacer domain of ADAMTS13 inhibit proteolysis of vWF , 234, whactivity . Also, sactivity . There iactivity .Contactin 1 (CNTN1), together with contactin-associated protein 1 (Caspr1), is expressed on the axonal surface and together they bind to neurofascin 155 on the surface of oligodendroglia –239. Thevia the lectin pathway . However, both the Kistler and the Ma studies have not yet been published in peer-reviewed journals and need further investigation. IgG4-mediated activation of the lectin pathway may not be the only pathogenic mechanism, as one patient with characteristic PLA2R-IgG4-positive MN was deficient for MBL but revealed complement activation via the alternative pathway  in primary MN], autoantigens such as PLA2R, and complement beneath the basal surface of podocytes in the kidney. PLA2R-IgG4 was proposed to have a unique mechanism of complement activation  pathway , 109. Th pathway , 98 that pathway  and IgA  pathway . MBL bin pathway . Prelimi pathway . Additio pathway , and a s pathway . Additio pathway . An addi pathway . In anot pathway , 246. Fu pathway ]. Therefin vitro were shown to affect cytoskeletal architecture with the formation of stress fibers in cultured primary murine podocyte cells and could also induce detachment of THSD7A overexpressing HEK293 cells , contactin-associated protein 2 (Caspr2), and Neurofascin155, respectively, a pathogenic mechanism has been suggested that is based on the block of protein–protein interaction , 93, 248g., Ref. ], althoug., Ref. , 93, 249 ex vivo . These e ex vivo , 250–252 ex vivo . Importa ex vivo . Antibod ex vivo , 81, 84.IgLON family member 5 (Iglon5) is a CNS antigen and is targeted by autoantibodies in Iglon5 parasomnia, which is a severe autoimmune disease characterized by abnormal sleep behavior. Here, a population of pathogenic IgG1autoantibodies induced endocytosis of Iglon5   antibodies, the described pathogenic mechanism is the loss of DPPX and associated Kv4.2 from the cell surface, perhaps by antigenic modulation, which would require divalent binding and cross-linking of antigen. Unless an additional pathogenic mechanism is found for DPPX-IgG4, or alternatively, it is demonstrated that the loss of DPPX and Kv4.2 results from a mechanism that does not rely on divalent binding, it is not likely that DPPX encephalitis is an IgG4 autoimmune disease.Only one patient has been described with IgG4 subclass antibodies against Caspr1 , ain vitro models of pathogenicity.In summary, the pathogenicity of IgG4 in most IgG4 autoimmune diseases has not been proven yet. A key experiment could be the isolation of IgG4 subclass antibodies from patient serum or plasmapheresis material, followed by passive transfer to a suitable animal model, or to use purified IgG4 in already established H3 region that would remove its ability to undergo FAE. This possibility was investigated in several IgG4-associated diseases. In IgG4-RLD, sequencing showed that the FAE abolishing variant K409 was not present  pathogenic antibody of other class or subclass  and could have clinical implications for treatment decisions. Specifically, after the evaluation and classification of the proposed IgG4 autoimmune diseases, it emerged that in most cases several different antibody classes and/or subclasses are present in patient serum Table , and croFurthermore, pathogenic mechanisms were described for serum or IgG from patients with IgG4 autoimmunity that are likely not caused by IgG4 subclass antibodies as they depend on divalent binding or Fc effector function Figure , ADAMTS1Particularly interesting are Iglon5 autoantibodies in which an irreversible internalization of Iglon5 was shown. Here, a clear pathogenic mechanism of IgG1, depending on divalent binding , was shoSimilarly, DPPX antibodies cause a reversible loss of cell surface-expressed DPPX and Kv4.2, thus leading to hyperexcitation of neurons . This rein vitro  subclass and were pathogenic  animals . The exa animals . An earl animals . MuSK Ig animals . It woulAnother potential mechanism of MuSK IgG1–3 is the induction of MuSK endocytosis, which is also suggested to be part of the normal response of MuSK to agrin stimulation –283. OneIn TTP, antibodies of IgG, IgM, and IgA class are present; these may convey pathogenicity by the accelerated clearance of ADAMTS13 from the circulation , 284. ThIn patients with MN with anti-PLA2R abs, a subclass switch from IgG1 to IgG4 was reported over the course of the disease, with an inverse correlation with C1q involvement . It is tIn pemphigus, IgG1 antibodies against Dsg1 or 3 are present and they may also contribute to the blocking mechanism . AdditioTaken together, the presence of more than one pathogenic entity in IgG4 autoimmune diseases is quite possible and makes sense, if we consider that a rise of antigen-specific IgG4 in theory could have been an attempt of the immune system to dampen an inappropriate answer to the antigen by a different antibody species. This could also have clinical consequences, as monitoring of different Ig class/IgG subclass-specific autoantibodies may provide a deeper understanding of the autoimmune response, the individual antibody levels or a ratio thereof could be useful as biomarkers for disease progression or the selection of appropriate therapy.Two case reports describe the co-occurrence of MuSK MG or TTP with IgG4-RLD , 287, whA key characteristic in IgG4 autoimmunity is the presence of antigen-specific autoantibodies of IgG4 subclass with direct pathogenic function. In IgG4-RLD, the role of IgG4 is not well understood, but it is thought that IgG4 may have a blocking, anti-inflammatory function. There is indirect evidence for an antigen-driven pathogenicity, namely the presence of oligoclonal bands in the CSF of patients and the presence of oligoclonal expansions of somatically hypermutated IgG4+ B-cell clones, but these were not associated with any known autoantigen –296. OnlThe etiology of most autoimmune diseases and thus of most IgG4-mediated autoimmune diseases is not known, but there are a few interesting observations that could give a clue to potential factors and mechanisms that may contribute to immunopathogenesis.Lutzomyia longipalpis) exposes the patient to salivary proteins, specifically LJM11, against which most humans then develop antibodies. While LJM11 itself is a non-pathogenic environmental antigen, mounting an immune response against it is thought to be protective against parasites  that are also transmitted by the bite of the sand fly  IgG4 autoimmune diseases may have a link to infection, generally thought to be conveyed by molecular mimicry, where antibodies against pathogens cross-react against self-antigen. The autoreactive B-cells in pemphigus showed a shared VH1–46 gene usage, and these were associated with few somatic mutations, which suggests that naïve B-cells that use VH1–46 genes are prone to react against Dsg3 . VH1–46  by Ref. ]. So farIn case of PLA2R antibody-positive MN, infection and molecular mimicry were proposed to potentially contribute to immunopathogenesis, as there is partial homology between PLA2R peptides and bacterial cell wall enzymes of Clostridium species , 321. A There are a few cases of TTP onset or relapse after vaccination –329. ThiOverexpression of antigen by tumors can trigger an autoimmune response. THSD7A-positive MN is associated with malignancy, as THSD7A itself may also play a role in certain cancers  and specIn recent years, many IgG4 autoantibodies were discovered, particularly against neuronal targets. By now, 14 different antigen targets have been described and suggested to play a causative role in “IgG4 autoimmunity” . Using aThe author confirms being the sole contributor of this work and approved it for publication.The author declares that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.


An experimental study of plain concrete specimens of water-cement ratio 0.55, subjected to 0, 15, 25, 40, 50 and 75 cycles of freeze-thaw was completed. The dynamic modulus of elasticity (DME), weight loss, compressive strength, tensile strength, flexural strength, cleavage strength and stress-strain relationships of plain concrete specimens suffering from freeze-thaw cycles were measured. The experimental results showed that the strength decreased as the freeze-thaw cycles were repeated. A concise mathematic formula between DME, weight loss, mechanical properties and number of freeze-thaw cycles was also established. The influences of freeze-thaw cycles on the DME, weight loss and mechanical properties were analyzed. The experimental results serve as a reference for the maintenance, design and life prediction of dams, hydraulic structures, offshore structures, concrete roads and bridges in cold regions. Since the emergence and first practical use of concrete as a building material in the late nineteenth century, concrete has become one of the most versatile and widely produced materials in the world. Increasing population and living standards in both developing and developed countries will lead to an ever increasing demand for concrete materials. It has been predicted that concrete will continue to be the most popular industrial material . Neverthetc.Concrete has the potential to be damaged if it is subjected to freeze-thaw cycles. The American Concrete Institute (ACI) has established specifications for the protection of concrete placed during cold weather. The ACI defines cold weather as period when more than three successive days have a mean daily air temperature less than 40 F (Fahrenheit). It is thus important to fully understand the mechanical characteristics  of plainet al. [et al. [et al. [Sun et al.  investiget al.  outlined [et al.  investig [et al.  investig [et al.  introducTest Method of Long-Term and Durability on Ordinary Concrete GB/T 50082-2009 [The dynamic modulus of elasticity and weight loss were the main focus for most previous research on plain concrete suffering from freezing and thawing cycles. These studies, however, did not provide information on the strength and deformation of concrete under uniaxial compressive stress states, especially information on the strength and deformation of the concrete specimens under uniaxial tensile stress states. Hence, this paper studied the compressive strength, tensile strength, cleavage strength, flexural strength and the ultrasonic velocity of plain concrete specimens with water-cement ratio 0.55 after different cycles of freeze-thaw according to the 082-2009 .3), sand (611 kg/m3), Coarse aggregate (1241 kg/m3), Water (198 kg/m3). The mixing was accomplished after putting all the coarse and fine aggregate into the mixer. These ingredients were mixed for about one minute, then the water was added within one minute. The mixing continued for about two minutes after all water was added. And then the air content (it was 1.9%) was measured. In this investigation, local materials were utilized. A Chinese standard (GB175-2007)  Type I 4Concrete prisms with size of 100 mm × 100 mm × 100 mm  and 100 mm × 100 mm × 400 mm  were cast in steel molds. The major stress direction was always applied to surface which was perpendicular to the ground surface. All cast specimens (the number of the test specimens is 106) were compacted through external vibration and demolded 24 h later. Thereafter, all the specimens were cured in a condition of 20 ± 3 °C and 95% Relative Humidity (RH) for 23 days. Some of the specimens (the number of the specimens was 85) were then immersed in water for 4 days prior to the freeze-thaw cycles.Test Method of Long-term and Durability on Ordinary Concrete GB/T 50082-2009 at the age of 28 days. The temperature of concrete samples was controlled by a Pt sensor embedded in the center of the concrete sample. The temperature of the sample center ranged from −17 ± 2 °C to 8 ± 2 °C. In a single cycle, the temperature of the specimens cools from 6 °C to −15 °C and then warmed to 6 °C all within 2.5–3 h in water. The compressive strength, tensile strength, stress-strain curve, dynamic modulus of elasticity and weight loss of the specimens were tested and recorded at 0, 15, 25, 40, 50 freeze-thaw cycles. At least three specimens were measured for each testing item. Three layers of butter and three layers of plastic membranes were used as a friction-reducing pad when compressive strength was tested.The freeze-thaw cycling test was performed following the The tensile tests were conducted in a special triaxial testing machine   and weight loss of plain concrete of water-cement ratio 0.55 after accelerated freeze-thaw cycling tests are given in D is the relative dynamic modulus of elasticity, N is the number of freeze-thaw cycles, correlation coefficient is 0.998.The dynamic modulus of elasticity is the proportion of stress to strain when the stress is least under the action of dynamic loads. The dynamic modulus of elasticity can be measured by means of longitudinal vibration or flexural vibration. It reflects the elasticity performance of material, similarly to the initial tangential modulus under static loads. The loss of the dynamic modulus of elasticity with freeze-thaw cycles means the loss of the elasticity performance. The RDME is the ratio of the dynamic modulus of elasticity measured after a certain number of freeze-thaw cycles to the initial value prior to freeze-thaw cycles. As W is the weight loss after different cycles of freeze-thaw, correlation coefficient is 0.995.Equation (2) gives the relationship between the weight loss and number of freeze-thaw cycles:The weight loss of concrete specimens is caused by surface separation or scale off. The rate of freeze-thaw cycling in the laboratory conditions was much higher than in the natural environment. Thus, it is reasonable that the scaling observed was more severe during the freeze-thaw cycles. The reason is as follows: the weight variation of concrete was caused by water movement and surface separation. Concrete is a three-phase composite structure at microscopic scale, a mortar matrix, aggregate and the interfacial transition zone between the two. Microcracks exist at cement paste-aggregate interfaces within concrete even prior to any load and environmental effects. In repeated cycles of freeze-thaw in a wet environment, water will enter the cracks during the thawing process of the freeze-thaw cycle. If the mass of surface separation is larger than the water absorbed by the concrete specimens, the weight of the concrete specimens will decrease.2). These values were then used in the analysis of the test results. In this paper, compression is denoted as negative, tension as positive. The tensile stress and the compressive stress were, respectively, calculated by dividing the tensile load and the compressive load by the area of loading section  and (4) were given in F is the failure load, A is the area under cleavage load.The cleavage strength can be drawn through the Equation as following :(5)fts=P is the failure load, l is the span of support, b is the width of section of concrete specimen, h is the height of section of concrete specimen.The flexural strength can be drawn through the Equation as following :(6)fctmAs seen from The computed results of the flexural strength and cleavage strength according the Equations (7) and (8) were given in Ultrasonic velocity is the speed at which sound travels through a given material. It is affected by density and elasticity. Velocity remains constant in a given material. After 0, 25, 50, 75, 100 cycles of freeze-thaw, the decreasing percentage of the ultrasonic velocity is 100%, 92.08%, 85.45%, 72.69% and 61.65% respectively. It can be seen the ultrasonic velocity decreased as freeze-thaw cycles were repeated. After 50 cycles of freeze-thaw, the RDME decreased to 46.8%, while the compressive strength, tensile strength, flexural strength and cleavage strength decreased to about 50.6%, 43.5%, 54.1% and 55.4% of the initial value, respectively. According to GB/T 50082-2009 and the ASTM C666 Standard Test , the speThe effect of freeze-thaw cycles on the dynamic modulus of elasticity, compressive strength, tensile strength, flexural strength and cleavage strength compressive strength is presented in Concrete is a three-phase composite structure at microscopic scale, a cement matrix, aggregate and the interfacial transition zone between the two. On the other hand, in considering the concrete specimen under the compressive load, tensile load, cleavage load, the initiation and growth of every new crack, the load carrying area will be reduced. This reduction in load carrying area causes a further increase in the stress concentration at critical crack tips. The effective area becomes thus little when the specimen suffers from compressive load, tensile load, cleavage load and the concentration of stress is caused again. The strength decreased as freeze-thaw cycles increased.(1)The compressive strength, tensile strength, flexural strength and cleavage strength decreased as the freeze-thaw cycles increased. The loss of compressive strength and tensile strength after the action of freeze-thaw cycles was evident. According to GB/T 50082-2009 , the con(2)The stress-strain curves of concrete under uniaxial compression went flat as the freezing and thawing cycles increased. The peak value of strain under uniaxial compression increased with freeze-thaw cycles increased, while the peak value of strain under uniaxial tension decreased with freeze-thaw cycles increased. (3)The results will help enable structure design and maintenance by considering the freeze-thaw durability of concrete. Therefore, in deciding the damages in concrete caused by freezing, the study of the ice formation process in concrete pores is critical.Based on the experimental work in this study and the discussion about the test results, the following conclusions can be drawn:


One of the most efficient and environmentally friendly methods for preventing a landslide on a slope is to vegetate it. Vegetation-pervious concretes have a promising potential for soil protection. In this study, the vegetation-pervious concrete with low alkalinity was developed and studied. Combined with a grid beam structure system, the stability and strength between the vegetation-pervious concrete and base soil are believed to be enhanced effectively. For improving plant adaptability, the alkalinity of concrete can be decreased innovatively by adding a self-designed admixture into the cement paste. The effects of the admixture content on alkalinity and compressive strength of the hardened pervious concrete were investigated using X-ray diffraction (XRD) and compression test, respectively. Meanwhile, the permeability of the vegetation-pervious concrete was studied as well. Through comparing with ordinary pervious concrete, the effect of low alkaline pervious concrete on vegetation growth was investigated in a small-scale field for ten weeks. The test results indicated that the alkalinity of the cement samples decreased with the increase of admixture content, and the vegetation grew successfully on previous concrete. By increasing the admixture content to approximately 3.6%, the compressive strength of pervious concrete was more than 25 MPa. Cement based materials, such as concrete and cement mortar, are one of the most widely used building materials in world. With development of science and technology, concretes with special functions were prepared and developed ,2. More Slopes are the most common landforms on Earth. Excluding natural slopes, large-scale infrastructure and urbanization constructions have created a large number of man-made slopes in China ,4,5. UnpContinuous grid beam structures made of concrete have been used for many years in China to stabilize the natural and man-made slopes. Generally, this slope stabilization structure is called “Grid Beam”. However, the soils within the frame of grid beams are vulnerable to be washed away during heavy rain. One of the fastest and most environmentally friendly methods for preventing or remedying a runoff on a slope is to vegetate it . Many reIn practice, surface drainage can successfully reduce the runoff of a slope . Soil-ceThe ideal vegetation-pervious concrete consists of a large number of connected pores, which are filled with suitable materials that contain moisture and nutrients needed by plants. The plant roots are able to grow and extend through the pores to form an integrated system of concrete and plant matter. For application to the construction industry, several important characteristics should be considered: (1) vegetation-pervious concrete must feature high strength and relatively good durability ,16, and 2 that accounts for 20%–25% of hardened cement samples. Thus, the concrete is found to be strongly alkaline, with pH value up to 12–13 [−) and molecular sieve effects based on their studies on the formation and manifestation of alkaline solution in concrete pores through a series of means such as physical, geotechnical and biochemical methods. They also proposed more than ten methods e.g., using a modifier to not only adjust the pH value in Portland cement concrete pores to 7–7.5, but also to increase their buffer capacity, which can be defined as the maximum amount of either strong acid or strong base that can be added before the occurrence of a significant change in pH. Consequently, the concrete was found more favourable to plant growth, and its durability was also improved.However, vegetation-pervious concrete, which is suitable for vegetation growth while maintaining water drainage and mechanical properties, is challenging to be obtained. The greatest challenge is the vegetal properties of this type of concrete. The hydration reaction of cement generates Ca(OH)to 12–13 ,20. Due to 12–13  and highto 12–13  for greeto 12–13  proposedAlthough conventional methods can reduce the alkalinity of pervious concrete, the main problem identified in current research of vegetation-pervious concrete is that the conventional methods of reducing alkalinity tend to weaken the physical and mechanical properties of vegetation-pervious concrete when compared to the control concrete. Therefore, the primary goal of this study was to propose a method to reduce the alkalinity of pervious concrete for vegetation at the same time maintaining the mechanical properties of the concrete. Chemical and mineral admixtures have been extensively used to adjust or modify the properties of fresh and hardened concrete . In thisIn this research, the method of adding a self-designed admixture, which is named Reducing Cement Alkaline (RCA), was employed to reduce the alkalinity of concrete. Portland cement (PC) Type 42.5R, which conforms to British Standard BS EN 197-1 CEM I , was use3 (about USD 43/m3). Other researchers who are interested in similar area can do a cost benefit analysis based on the cost information and their project characteristics.In China, at present, the costs of the vegetation-pervious concretes produced by manufacturers are less than RMB 300/mIn this study, the procedures for sample preparation are described as follows. First, part of the mixing water was added into the coarse aggregate and stirred until the gravel surface was wet. Second, the cement was added and the mixture was stirred for approximately 30 s to allow the gravel surface being coated with a layer of cement paste. Third, the remaining mixing water and the admixture RCA were added. The mixture was then stirred continuously for about 3 min, until the cement paste coating on gravel thickened. Finally, the mixture was cast into a 100 mm × 100 mm × 100 mm mould in three steps. Moulds were filled with the mixed concrete up to one-third of the height of the mould and subjected to 25 times hand tamping. The same procedure was applied for the two-third and complete fill-ups. The vegetation-pervious concrete was removed from the mould after 24 h and cured for 28 days in a controlled environment , which is similar to the process for conventional concrete.A control mix and four hardened cement paste mixes with different proportions of the admixture RCA  were analysed. The water/cement ratio was 0.35. Cubes with a size of 100 mm were used for studying the compressive strength at 4, 7, and 15 days after standard curing in a controlled environment . The compressive test was performed according to the China national standard GB/T 50081-2002 . Three sIn this study, different properties of vegetation-pervious concretes were investigated. D) × 100 mm (H). The test procedure for the porosity of vegetation-pervious concrete was as follows:(1)M1) was measured.The sample was dried in an oven at 60 °C until the mass did not change, and the mass ((2)Vcylinder) was calculated.The diameter and height of the sample were measured, and the volume of the sample ((3)M2) was measured by a hydrostatic balance method as shown in The samples will be soaked in water for 2 h for getting a saturated station. The mass of saturated sample ((4)P) of the sample was calculated using the following equation:P is the porosity of the sample, %; M1 is the sample mass in air, gram; M2 is the mass of the sample in water, gram, ϱwater is the water density, g/mm3; and Vcylinder is the volume of the sample, mm3.The porosity (Sample used in this test is cylinder with the dimensions 100 mm ((1)D) and thickness (L) of the cylindrical samples were measured twice using callipers, and the data were averaged to 0.1 cm. Then, the sample surface area (A) was calculated.The diameter ((2)The sidewall of the cylinder was sealed by a watertight material (epoxy). The epoxy was brushed on the sidewall of the samples evenly and the thickness of epoxy was more than 1 mm. The water was allowed to penetrate the sample from the upper and lower surfaces. After the watertight material was cured, the sample was placed in water to a water-saturated state before the test.(3)t (seconds) and quantity of water outflow (Q) were measured three times, and the data were averaged.The sample was not removed from the water until the permeability test was performed. The sample was connected with the permeable tube shown in (4)H), which was accurate to 0.1 cm, between the water level in the water tank and the water level of the permeable tube was measured by a rule.The distance ((5)K) of the sample can be calculated as the following equation:K is the permeability coefficient of the tested sample, mm/s; Q is the quantity of water outflow within time t, mL; L is the thickness of the sample, mm; A is the upper surface of the sample, mm2; H is the distance between the levels, mm; and t is the testing time, s.Permeability coefficient  were used to measure strains for calculating elastic modulus. Before sticking the strain gages, the two sides of the cylinders needed to be flattened using cement paste, and the sizes of flat areas were about 60 mm length and 20 mm width, and the position of the areas was the centre of the cylinder height. After the cement paste hardened, the strain gages were adhered at the flat areas. After the compression test, the hardened cement pastes coated on the aggregate surfaces of the failure samples were collected and ground into powder to measure the amount of chemical elements in the hardened cement paste samples by using X-ray Diffraction (XRD). A Mercury AutoPore IV 9500 injection apparatus  was used for the pore analysis of the plain cement paste, and the XRD analysis was conducted using a DX—2500 X-ray diffractometer . These tests involved a Cu target, 3 kW of power, 0.03° per step and a scanning range from 5° to 70°. To avoid carbonation during grinding the cement pastes, the samples were ground in 100% alcohol and dried in a vacuum oven at 60 °C for 48 h.L) × 400 (W) × 150 mm (H). The pores of concrete specimens were grouted with mulching material (nutrient soil), which was able to retain water and fertilizer, as shown in In this study, the vegetation-pervious concrete with 3.6% admixture RCA was chosen to conduct the vegetation test, and a pervious concrete without admixture RCA was used as a control sample. All concrete specimens were employed as vegetation beds and exposed to a natural environment. In the experiment, the vegetation-pervious concrete cubes were placed in a wooden box with the dimension of 400 . The higher strength and larger strength range of vegetation-pervious concrete yield an extensive range of applications for slope protection. Specifically, when the admixture content was 3.6%, the strength substantially increased to 25.2 MPa, which is much greater than the strength range of 5–15 MPa, as reported in the previous studies ,37,38,39Elastic modulus and compressive strength are the two important properties used for the design of pervious concrete for slope protection. Although the effect of aggregates on compressive strength has been analysed, few studies have revealed the effect of admixture on the static modulus of elasticity of vegetation-pervious concrete. Static modulus can influence the deformation of vegetation-pervious concrete directly. As shown in 2) in the hardened cement samples. The intensity of the Ca(OH)2 crystal peaks in the XRD spectra was employed as an index to characterize the alkalinity of the sample. 2 in the mixes for various curing times. The peaks in the XRD curves correspond to the mineral Ca(OH)2, and the intensity of the main peaks reflect the Ca(OH)2 contents in the cement samples.In this study, the alkalinities of hardened cement pastes from concretes with different admixture dosages were measured by XRD analysis. The levels of alkalinity were compared based on the amount of calcium hydroxide (Ca(OH)The alkalinity of all cement paste mixes with admixture was initially lower than that of the cement paste mixes without admixture. The cement paste with admixture contents between 1.2% and 3.6% showed a decreasing trend in alkalinity with days of curing, and their alkalinity were even much lower than that of control samples after curing for 14 days see . HoweverBased on the above results and observation, it can be known that when the admixture content between 2.4% to 3.6% is added, the strength of vegetation-pervious concrete can be improved, whereas its alkalinity can be reduced.The growing status of Bahia grass planted on the surface of ordinary vegetation-pervious concrete (without admixture) over ten weeks of exposure to the natural environment is shown in As shown in these photos, Bahia grass started germinating typically one week after sowing; however, the grass began to wither after three weeks and died after five weeks. It is interesting to note that some Bahia grass and weeds were found to grow well in the surrounding soils or within the gap of concrete blocks in five weeks. After the ten-week observation, the plants eventually failed to grow on the concrete surface. Neither the soil in the pores of the concrete nor the soil above the concrete surface was suitable for plants because the alkalinity of this soil was higher than the alkalinity of the surrounding soil. This conclusion can be supported by XRD test results in 2) among RCA additive chemically reacted with an alkaline substance (Ca(OH)2) to generate calcium silicate hydrates (C–H–S), which resulted in the decrease of alkalinity of the vegetation-pervious concrete and formation of a dense layer that effectively prevented the alkaline substance dissolving out from the concrete to the soil.As shown in (1)The compressive strength and elastic modulus of the vegetation-pervious concretes increased with the increase of admixture, but the effect of admixture on elastic modulus was less significant compared to the compressive strength. The result showed that vegetation-pervious concretes with admixture showed lower alkalinity and higher strength. Therefore, the admixture used in this study was not only able to decrease the alkalinity of cement effectively but also improve the strength to as high as 25.2 MPa at an admixture content of 3.6%.(2)In comparison, the alkalinity of the cement cube samples with admixture was lower than that of the cement paste mixes without admixture. When the admixture content between 2.4% to 3.6% was added, the strength of vegetation-pervious concrete was found improved, whereas its alkalinity was reduced.(3)Compared with a traditional method, the developed vegetation-pervious concrete slope protection method can be adapted for different vegetation requirements and slope gradients by adjusting alkalinity and porosity of the concrete.(4)Based on the test results of alkalinity, permeability coefficient and mechanical properties of the studied concretes, the vegetation-pervious concretes have demonstrated their potential suitability when using in continuous grid beam structure for slope protection.This paper demonstrated the use of an admixture method to reduce the alkalinity of vegetation-pervious concrete to create favourable conditions for vegetation growth. A vegetation-pervious concrete for soil slope protection was developed. Based on the results presented here, the following conclusions were drawn:


Cognitive abilities are essential for children’s development and independence. Various cognitive assessments, standardized in Western cultures, have yet to be investigated for their multicultural suitability.To explore the suitability of the Loewenstein Occupational Therapy Cognitive Assessment (LOTCA) for a Jordanian population.Observed cases of 442 Jordanian children aged 6–12 were used to perform exploratory factor analyses using principal components with Varimax rotation  and to compute Cronbach’s α coefficient .High total performance on four subscales and a slightly lower total performance on two subscales were observed. Observed performance increased with age on three subtests, whereas a more modest increase was observed on the other three subscales. The expected one-factorial solution confirming the LOTCA’s subscales homogeneity  structure was found on five of six subscales. Variance explained by the subscales ranged from 39 to 82% and internal consistency reliability measured by Cronbach’s alpha ranged from .42 to .78.Satisfactory construct validity and internal consistency reliability were demonstrated on two subscales applicable to Jordanian children without adaptation. With adequate cross-cultural adaptation, increasing internal consistency reliability in other subscales could make the LOTCA an effective tool for assessing cognitive abilities in this population. Cognitive abilities are skills that form the basis for every human action and enable the performance of tasks ranging from the simple to the complex. Such abilities, including perceptual discrimination, selective attention, memory, and language, are modified by the context in which they developed  and reprChildren vary in their underlying cognitive abilities to process and use information, and these differences affect a child’s learning and academic performance . Indeed,Furthermore, each culture has its own patterns of practices that affect children’s development, behaviors, skills, and attitudes, as well as cognitive performance , 4, 9. C, there are several standardized assessments and screening instruments used by therapists and researchers in the area of cognitive abilities . While the total mean score of the other two subscales is slightly lower, performance on these subscales is still quite high: [visuo-motor organization, M = 22.35 (SD = 4.23) - composite scores ranging from 7 to 28; thinking operations, M = 24.71  and three moderate to good coefficients ranging from . These correlations suggest that all subscales measure the same construct and provide satisfactory levels and evidence of construct validity.As shown in Table orientation generated the expected one-factor solution with an eigenvalue of 1.64, confirming the LOTCA’s homogeneity  factor structure and thus providing construct validity evidence. Accounting for approximately 82% of the variance, with a Cronbach’s α of .76, results show a satisfactory level of internal consistency reliability. Therefore, this subscale may be used with Jordanian children ages 6 to 12 without cross-cultural adaptation  factor structure and providing adequate construct validity evidence. Accounting for approximately 44% of the variance with a Cronbach’s α .78 this subscale exhibits a satisfactory level of internal consistency reliability. Consequently, this subscale may be used with Jordanian children ages 6 to 12, without cross-cultural adaptation  and Cronbach’s α for the subscale visual perception yielded an expected one-factor solution with an eigenvalue of 1.58, confirming the LOTCA’s homogeneity  factor structure and providing an adequate level of construct validity accounting for approximately 40% of the variance. The Cronbach’s α of .47 does not provide a satisfactory level of internal consistency reliability. This subscale may not be used with Jordanian children ages 6 to 12 without adequate cross-cultural adaptation to increase its internal consistency reliability  factor structure for this subscale, demonstrating a satisfactory level of construct validity evidence. This solution accounted for approximately 58% of the variance. Cronbach’s α was .63, indicating a questionable level of internal consistency reliability. Consequently, this subscale may not be used with Jordanian children ages 6 to 12 without cross-cultural adaptation to increase its internal consistency reliability  factor structure demonstrating a satisfactory level of construct validity. This solution accounted for approximately 52% of the variance. Cronbach’s α was .47, exhibiting an unacceptable level of internal consistency reliability evidence. Consequently, this subscale may be not be used with Jordanian children ages 6 to 12 without cross-cultural adaptation to increase its internal consistency reliability evidence  factor structure of this modified subscale was confirmed, demonstrating unacceptable level of construct validity. This solution accounted for approximately 44% of the total variance. Cronbach’s α was .74 exhibiting a satisfactory level of internal consistency reliability. Although construct validity and internal consistency reliability evidence were established, this modified subscale may not be used with Jordanian children ages 6 to 12 without a significant cross-cultural adaptation designed to further study the possible consequences of eliminating the item Pictorial B from the subscale  factor structure of the LOTCA subscales was not confirmed.The EFA generated five one-factor solutions and one two-factor solution, confirming the expected homogeneity  factor structure of the items within five of the six LOTCA subscales. All solutions had eigenvalues that satisfied the thinking operations subscale involves higher mental processes such as executive function, problem solving, abstraction, and logical operation [thinking operations was the most sensitive subscale for identifying differences between the ID and the healthy groups [The peration  and sociperation . Therefoy groups .-loading situations are usually eliminated from the analysis [The item Pictorial Sequence B was loaded above the cutoff point on both factors, becoming a cross loading item , 32. A panalysis , 32. In The pictorial sequence has various underlying components, such as cognitive abilities of judgment, sequence, organization, and comprehension, which may already be measured by other items in the thinking operations subscale. A cross-cultural adaptation process can help assess whether the subscale contains enough information to adequately cover what it is intended to measure without this specific item.Orientation, Spatial Perception, Motor Praxis and Thinking Operations subscales loaded above the established cutoff point, ranging from .61 to .91. It is important to note that the loadings of these items demonstrated a satisfactory construct validity evidence for these subscales [In the present study, the criterion for determining whether an item loaded substantially on a subscale was established at .50 . In twenubscales . The relubscales .Object Identification (.47), part of the Visual Perception subscale and Two Dimensional Model (.48), part of the Visomotor Organization subscale, were slightly below the cut-off point. These relatively low loadings show that their contribution to each subscale is less meaningful [Visual Perception and Visu-Motor Organization subscales are not sufficiently accounted for by their items and thus do not demonstrate satisfactory evidence for construct validity for these subscales [Object Identification and Two Dimensional Model are simple items, originally prepared for people with brain injuries. Thus, it is not surprising that TD children completed these items easily and obtained high scores on them, creating a ceiling effect.The loadings of the item aningful . These fubscales . Object These findings affect the ability of Arabic speaking Jordanian clinicians to interpret the composite score of these subscales as a reflection of all the subscale items . Thus, fOrientation, Visomotor and Thinking operations subscales. For example, Visomotor and Thinking operations were significantly correlated at the .69 level. Hence, the skills needed to perform the Visomotor subscale are also the basis of the Thinking operation subscale and indicate a satisfactory degree to which the items comprising each subscale measure the same construct [Visomotor organization, its underlying components include a categorization component, such as which color the subject should choose. Such item homogeneity directly affects the ability of a Jordanian clinician to interpret the LOTCA composite clinical score as a reflection of all the measures comprising each of these subscales. The items on these subscales are correlated with each other regardless of culture differences.In the present study, the estimates of internal consistency reliability were obtained using Cronbach’s alpha. As the coefficient alpha is affected by test length and subject to inflation, it has been suggested that alpha should be calculated for each of the subscales rather than for the entire test , 35, 36.onstruct  in the pSpatial Perception, indicating an insufficient ability to measure the same construct. In a previous study  which compared the cognitive functioning of Israeli and Palestinian children using the LOTCA, the spatial perception subscale was included in different factors in each group. In the Israeli group, spatial perception was included in a factor named Visuo-motor organization and sequence abilities and loaded .62 while in the Palestinian group it was included in a factor named temporal and spatial perception and loaded .45. The study authors noted that these findings were due to cultural differences such as age of entry to the educational system and engagement in different cognitive tasks.A questionable level of internal consistency reliability evidence (α = .63) was found for the subscale Visual Perception and Motor Praxis subscales, clearly indicating that the measures comprising these subscales do not jointly measure the same construct and lack item homogeneity. Since the subscale’s measures are linearly combined into a composite score, the concern for item homogeneity directly affects the ability of clinicians to interpret composite scores on these subscales. Since the evidence of measures of homogeneity was absent, these subscales require cultural adaptation before they can be of utility to Arabic speaking Jordanian clinicians.Unacceptable levels of internal consistency reliability evidence (α = .47) were found for the Orientation, Visu-Motor and Thinking subscales was within satisfactory level of internal reliability (76), indicating a relatively low level of error variance for the measures contained in each of these subscales; thus they can be considered reliable as a single construct even without cultural adaptation. The Cronbach’s alpha for the other three subscales, Spatial Perception, Visual Perception and Motor Praxis, was below the accepted level of internal reliability, indicating a high level of error variance for the measures contained in these subscales to be considered as a single construct. This might be due to the high dimensionality in the measures, more often associated with low values for Cronbach’s alpha while not necessarily indicating that the measures are not adequate or reliable [The value of Cronbach’s alpha for the reliable . The extAlthough there are several important implications for the current study, some limitations should be addressed. First, future psychometric research on the LOTCA should include other aspects of validity and reliability not undertaken in the present study. There is also a need to assess the association between test performance and academic achievement. Second, children with known disabilities were excluded from the current study. While including those children might have added to the discriminating value of the LOTCA, it is recommended to address this issue in future studies. Third, the administration and especially scoring of the LOTCA requires some training of personnel, because not all items are non-verbal. Therefore, some items are not suitable for people with hearing/speech problems. In addition, the test is time-consuming. Therefore, it might be that some aspects of the results are attributable to instrument administration.Orientation and Visu-motor organization. The one-factor solutions obtained for each subscale confirmed the LOTCA subscale homogeneity  structure and the above-satisfactory levels of Cronbach’s alpha attested to the consistency of the measures within these subscales and hence, to satisfactory internal consistency reliability evidence. These findings suggest that these two subscales were found to be free of cultural bias and could be used with Jordanian children without the need for cultural adaptation. With adequate cross-cultural adaptation efforts to adapt the other four subscales, the LOTCA may be used as an effective tool for assessing cognitive abilities with Jordanian children ages 6 to 12. Future research should include additional representative samples. Future psychometric research on the LOTCA to include other aspects of validity and reliability not undertaken in the present study is also needed, as well as assessing the association of test performance with academic achievements.The translation and use of the LOTCA demonstrated satisfactory evidence of construct validity and internal consistency reliability in two subscales,