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Objectives: To assess the predictors of ghost infarct core (GIC) in stroke patients achieving successful recanalization after mechanical thrombectomy (MT), based on final infarct volume (FIV) calculated from follow-up diffusion-weighted imaging (DWI). Methods: A total of 115 consecutive stroke patients who had undergone baseline computed tomography perfusion (CTP) scan, achieved successful recanalization after MT, and finished follow-up DWI evaluation were retrospectively enrolled. Ischemic core volume was automatically generated from baseline CTP, and FIV was determined manually based on follow-up DWI. Stroke-related risk factors and demographic, clinical, imaging, and procedural data were collected and assessed. Univariate and multivariate analyses were applied to identify the predictors of GIC. Results: Of the 115 included patients (31 women and 84 men; median age, 66 years), 18 patients (15.7%) showed a GIC. The GIC group showed significantly shorter time interval from stroke onset to CTP scan and that from stroke onset to recanalization (both p < 0.001), but higher ischemic core volume (p < 0.001), hypoperfused area volume (p < 0.001), mismatch area volume (p = 0.006), and hypoperfusion ratio (p = 0.001) than the no-GIC group. In multivariate analysis, time interval from stroke onset to CTP scan (odds ratio [OR], 0.983; p = 0.005) and ischemic core volume (OR, 1.073; p < 0.001) were independently associated with the occurrence of GIC. Conclusions: In stroke patients achieving successful recanalization after MT, time interval from stroke onset to CTP and ischemic core volume are associated with the occurrence of GIC. Patients cannot be excluded from MT solely based on baseline CTP-derived ischemic core volume, especially for patients with a shorter onset time. Key Points: • Ghost infarct core (GIC) was found in 15.7% of patients with acute ischemic stroke (AIS) in our study cohort. • GIC was associated with stroke onset time, volumetric parameters derived from CTP, and collateral status indicated by HIR. • Time interval from stroke onset to CTP scan and ischemic core volume were independent predictors of GIC. [ABSTRACT FROM AUTHOR]

Background: Volumetric accuracy of using computed tomography perfusion (CTP) to estimate the post-treatment infarct in stroke patients with successful recanalization after mechanical thrombectomy (MT) has been studied a lot, however the spatial accuracy and its influence factors has not been fully investigated. Methods: This retrospective study reviewed the data from consecutive anterior large vessel occlusion (LVO) patients who had baseline CTP, successful recanalization after MT, and post-treatment diffusion-weighed imaging (DWI). Ischemic core on baseline CTP was estimated using relative cerebral blood flood (CBF) of < 30%. The infarct area was outlined manually on post-treatment DWI, and registered to CTP. Spatial agreement was assessed using the Dice similarity coefficient (DSC) and average Hausdorff distance. According to the median DSC, the study population was dichotomized into high and low Dice groups. Univariable and multivariable regression analyses were used to determine the factors independently associated with the spatial agreement. Results: In 72 included patients, the median DSC was 0.26, and the median average Hausdorff distance was 1.77 mm. High Dice group showed significantly higher median ischemic core volume on baseline CTP (33.90 mL vs 3.40 mL, P < 0.001), lower proportion of moderate or severe leukoaraiosis [27.78% vs 52.78%, P = 0.031], and higher median infarct volume on follow-up DWI (51.17 mL vs 9.42 mL, P < 0.001) than low Dice group. Ischemic core volume on baseline CTP was found to be independently associated with the spatial agreement (OR, 1.092; P < 0.001). Conclusions: CTP could help to spatially locate the post-treatment infarct in anterior LVO patients who achieving successful recanalization after MT. Ischemic core volume on baseline CTP was independently associated with the spatial agreement. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the feasibility of using CT perfusion (CTP) with increased temporal sampling interval to predict the target mismatch status in acute ischemic stroke (AIS) patients with anterior circular large-vessel occlusion (LVO). Methods: CTP with a sampling interval of 1.7 s (CTP1.7 s) was scanned in 77 AIS patients for pre-treatment evaluation. Simulated CTP data with sampling interval of 3.4 s (CTP3.4 s) or 5.1 s (CTP5.1 s) were reconstructed, respectively. Target mismatch was defined according to the EXTEND-IA (Extending the Time for Thrombolysis in Emergency Neurological Deficits—Intra-Arterial) and DEFUSE 3 (Endovascular Therapy Following Imaging Evaluation for Ischemic Stroke) trial criteria, respectively. Pearson correlation analysis, Mann–Whitney U test, Bland–Altman analysis, and chi-square test were used for statistical analysis as appropriate. Results: Significant correlations were found on the volume of ischemic core, hypo-perfused area, mismatch area, and ratio between CTP1.7 s and CTP3.4 s or CTP5.1 s (all p < 0.001). There was no significant difference on the volume of ischemic core, hypo-perfused area, mismatch area, and mismatch ratio between CTP1.7 s and CTP3.4 s or CTP5.1 s (all p > 0.05). Compared with CTP1.7 s, CTP3.4 s or CTP5.1 s showed comparable performance in predicting the target mismatch status in the AIS patients with LVO (both p > 0.05). Conclusions: CTPs with increased temporal sampling intervals that lead to reduced radiation doses are feasible and may provide comparable performance in predicting target mismatch status in AIS patients with LVO. [ABSTRACT FROM AUTHOR]

Background: Alberta Stroke Program Early Computed Tomography Score (ASPECTS) is a grading system to assess the extent and distribution of early ischemic changes. Purpose: To assess inter-rater agreement for total and regional ASPECTS on non-contrast computed tomography (NCCT) images, CT angiography source images (CTA-SI), and CT-perfusion cerebral blood volume (CTP-CBV) maps, and their association with final infarction in patients with acute ischemic stroke (AIS). Material and Methods: A total of 96 consecutive patients with AIS who underwent pre-treatment NCCT and CTP were retrospectively enrolled. CTA-SI was reconstructed using the raw data of CTP. Total and regional ASPECTS were assessed on baseline NCCT, CTA-SI, and CTP-CBV, and on follow-up NCCT or diffusion-weighted imaging. Follow-up ASPECTS served as the reference standard for final infarction. Results: CTP-CBV demonstrated higher concordance for total ASPECTS (interclass correlation coefficient, 0.895 vs. 0.771 vs. 0.777) and regional ASPECTS in internal capsule, lentiform, caudate nuclei, M5 and M6, compared with NCCT and CTA-SI. CTP-CBV showed a trend of stronger correlation with final ASPECTS than NCCT and CTA-SI (0.717 vs. 0.711 vs. 0.565; P > 0.05). ASPECTS in the internal capsule (ρ, 0.756 vs. 0.556; P = 0.016) and caudate nucleus (ρ, 0.717 vs. 0.476; P = 0.010) on CTP-CBV were more strongly correlated with follow-up ASPECTS than NCCT. CTP-CBV showed higher accuracy for predicting final infarction in the internal capsule (92.5% vs. 90.3% and 87.1%; P > 1.000, P = 0.125, respectively) and caudate nucleus (87.1% vs. 79.6% and 77.4%; P = 0.453, P = 0.039, respectively) than CTA-SI and NCCT. Conclusion: CTP-CBV ASPECTS might be more reliable for delineating early ischemic changes and predicting final infarction. [ABSTRACT FROM AUTHOR]

Steel jacketing and concrete jacketing are popular retrofitting techniques to strengthen the axial compressive behavior of reinforced concrete (RC) columns. However, these retrofitting methods lack efficiency in practical application due to intensive labor and time-consuming installation. In order to improve the retrofit efficiency of damaged RC columns, this study proposed a novel precast steel-reinforced grout jacket (PSRGJ) consisting of early-strength cementitious grout and a steel frame. Ten columns were tested to investigate the axial compressive behavior of predamaged RC columns retrofitted with PSRGJ. The tested parameters were the stirrup reinforcement ratio, the transverse reinforcement ratio of PSRGJ, and the predamage level. The results indicated that the columns' peak load and ductility index I 10 were significantly improved by PSRGJ retrofitting and increased with the increase of transverse reinforcement ratio of PSRGJ. Besides, the peak load and the initial stiffness of PSRGJ-retrofitted RC columns decreased with the predamage level, while the ductility index I 10 increased. In addition to the confinement effect, PSRGJ carried 11%−17% of the peak load through the interfacial bonding effect. Based on the test results, the actual confinement pressure model and interfacial bonding strength model were proposed. Further, peak load models considering the size effect were developed for PSRGJ-retrofitted intact and predamaged RC columns. The predictions of the proposed models agreed well with the test results from this study and the literature. • A precast steel-reinforced grout jacket (PSRGJ) was proposed to retrofit predamaged RC columns. • PSRGJ significantly improved the peak loads and ductility of predamaged RC columns. • PSRGJ carried 11%−17% of the peak load through the interfacial bonding effect. • Peak load models addressing the predamage and size effects were developed. [ABSTRACT FROM AUTHOR]

Background: Computed tomography (CT)-guided cutting needle biopsy (CNB) is an effective diagnostic method for lung nodules (LNs). The false-negative rate of CT-guided lung biopsy is reported to be up to 16%. This study aimed to determine the predictors of true-negative results in LNs with CNB-based benign results. Methods: From January 2011 to December 2015, 96 patients with CNB-based nonspecific benign results were included in this study as the training group to detect predictors of true-negative results. From January 2016 to December 2018, an additional 57 patients were included as a validation group to test the reliability of the predictors. Results: In the training group, a total of 96 patients underwent CT-guided CNB for 96 LNs. The CNB-based results were true negatives for 82 LNs and false negatives for 14 LNs. The negative predictive value of the CNB-based benign results was 85.4% (82/96). Univariate and multivariate logistic regression analyses revealed that CNB-based granulomatous inflammation (P = 0.013, hazard ratio = 0.110, 95% confidential interval = 0.019–0.625) was the independent predictor of true-negative results. The area under the receiver operator characteristic (ROC) curve was 0.697 (P = 0.019). In the validation group, biopsy results for 47 patients were true negative, and 10 were false negative. When the predictor was used on the validation group, the area under the ROC curve was 0.759 (P = 0.011). Conclusions: Most of the CNB-based benign results were true negatives, and CNB-based granulomatous inflammation could be considered a predictor of true-negative results. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate whether Alberta Stroke Program Early CT Score (ASPECTS) could provide incremental value to collateral score, and their integration could be an effective surrogate of CTP in predicting target mismatch. Material and methods: One hundred and fifty-nine stroke patients (onset time 6–16 h or with unknown onset time) with MCA and/or ICA occlusion underwent non-contrast computed tomography (NCCT) and CT perfusion (CTP) scan for initial assessment. Simulated single-phase CT angiography (sCTA, peak arterial phase) and multiphase CTA (mCTA) were reconstructed from CTP. ASPECTS was assessed on NCCT and sCTA. Collateral score was evaluated on mCTA. Target mismatch was defined as infarct core volume < 70 mL, the mismatch ratio ≥ 1.8, and the absolute mismatch volume ≥ 15 mL. Pearson correlation analysis, Mann–Whitney U test, chi-square test, and receiver operating characteristic curve analyses were performed. Results: Median CTA source image (CTA-SI) ASPECTS was significantly lower than NCCT ASPECTS (p = 0.001). NCCT ASPECTS, CTA-SI ASPECTS, and mCTA collateral score correlated significantly with infarct core volume and mismatch ratio (all p < 0.05). Mismatch group showed significantly higher NCCT ASPECTS, CTA-SI ASPECTS, and mCTA collateral score than non-mismatch group (all p < 0.001). NCCT ASPECTS and CTA-SI ASPECTS showed comparable predicting performance with mCTA collateral score (p > 0.05). Adding CTA-SI ASPECTS to mCTA collateral score improved the performance of mCTA in predicting target mismatch (area under curve, 0.905 vs. 0.804, p = 0.003). Conclusion: ASPECTS can provide incremental information to collateral score in predicting target mismatch. If CTP scan fails, clinical decision based on ASPECTS and collateral score might be reasonable. [ABSTRACT FROM AUTHOR]

Corrosion of steel reinforcements degrades the structural performance of reinforced concrete (RC) columns under static and seismic loads. Such corroded RC columns are usually retrofitted with fiber-reinforced polymer (FRP). However, existing studies on the retrofitting of RC columns with corrosion and load-induced damage are limited. To confirm the effectiveness of basalt FRP (BFRP) jacketing on the compressive behavior of corroded and pre-damaged RC columns, this study performed axial compression tests on eleven circular RC columns. The columns were fabricated, corroded, pre-damaged, and then jacketed with BFRP composites and reloaded to investigate the effects of BFRP layer number, corrosion ratio, and pre-damage degree. When jacketed by BFRP, the ultimate strength and ultimate strain of RC columns increased with BFRP layer numbers, ranging from 5% to 98% and 448% to 926%, respectively. Further, the ultimate strength and elastic modulus of the jacketed RC columns decreased with the increase in pre-damage degrees and corrosion ratios, while the ultimate strain was little affected. Buckling and corrosion of longitudinal bars significantly reduced the bar stresses at the ultimate state of BFRP-jacketed RC columns and resulted in local rupture of BFRP. This adverse effect became more pronounced as the corrosion ratio increased, but was alleviated by BFRP jacketing. On the other hand, a refined rebar stress-strain model was developed by addressing the effects of buckling, corrosion, and lateral confinement. Further, a feasible constitutive model for corroded hoop-confined columns was determined by validating the existing test results. Finally, models for the ultimate strength, ultimate strain, and stress-strain response of BFRP-jacketed corroded and pre-damaged RC columns were developed. • BFRP jacketing improved the axial compressive behavior of corroded and pre-damaged RC columns. • Increasing the corrosion ratios and pre-damage degrees decreased the strength and elastic modulus. • The effects of buckling, corrosion, and BFRP confinement on rebar ultimate stress were evaluated. • A stress-strain model was developed for BFRP-jacketed corroded and pre-damaged RC columns. [ABSTRACT FROM AUTHOR]

Minimizing earthquake damage and improving repair efficiency are the main principles of resilient structures. The present study proposed a repairable column with UHPC segments and replaceable internal buckling-restrained energy dissipaters. In the UHPC replacement segment, the buckling-restrained energy dissipaters were connected to rebars in other segments through threaded sleeve couplers and could be replaced after an earthquake event. The connected dissipater was unbonded to prevent premature low cycle fatigue failure. A UHPC transition segment was designed to prevent plastic hinge shifting. To evaluate the structural performance of the proposed column, cyclic loading tests were performed on two repairable columns using normal-strength dissipaters or hybrid high- and normal-strength dissipaters before and after repairing. The test results showed that compared with RC columns, the proposed columns exhibited significantly greater strength, deformation capacity, and energy dissipation, as well as low stiffness degradation. Use of high-strength dissipaters improved the strength and energy dissipation, but decreased the deformation capacity. After replacing the dissipaters and cover UHPC, the strengths and energy dissipation of the repaired columns slightly decreased, while the ultimate displacements were almost the same, showing satisfactory seismic resilience. Further, a stress-strain model for the unbonded buckling-restrained energy dissipaters and a flexural strength model for the original and repaired columns were proposed, which were compared with the existing test results. • A repairable column with UHPC segments and replaceable buckling-restrained energy dissipaters was proposed. • The proposed columns exhibited low damage, and buckling of the dissipater was successfully prevented. • The proposed columns showed higher strength, ductility, and energy dissipation than RC columns. • The strength and ductility of repaired columns were similar to those of the original columns. • Flexural strength models for intact and predamaged UHPC columns were proposed. [ABSTRACT FROM AUTHOR]

• For the specimens using D20 GFRP bars, the retrofit method of CE was sufficient to restore the bond strength. • For the specimens using D28 GFRP bars, the retrofit methods of U and CU were effective in restoring the bond strength. • The predictions of flexural strength and effective moment of inertia of retrofitted specimens were proposed addressing the pre-damage effect. Fiber-reinforced polymer (FRP) reinforced concrete structures are inevitably subjected to extreme loads. The retrofitting of damaged FRP-reinforced concrete structures will become an important issue, especially with the gradual application of FRP bars in concrete structures. For structures that can be retrofitted, the structural performance is significantly affected by the bond of FRP bars in pre-damaged concrete. For this reason, this paper investigated the effectiveness of retrofit methods of carbon FRP (CFRP) sheet and/or ultra-high performance concrete (UHPC) at restoring the bond strength of glass FRP (GFRP) bars in pre-damaged concrete, and twenty spliced GFRP-reinforced concrete beams were tested under four-point loading. The beams were pre-loaded until bond failure occurred, and then retrofitted and reloaded to assess the restoration of the bond strength. The effects of retrofit methods, spacing of confining stirrups, GFRP bar diameter, and pre-loading type were investigated. The bond strength of the 20 mm and 28 mm diameter GFRP bars was increased by 4~138% and 4~234% after retrofitting with CFRP sheet and/or UHPC, respectively. The modified flexural strength model and modified effective moment of inertia addressing the adverse effect of partial fracture of glass fibers and concrete cracks predicted well the load-carrying capacity and deflection of the retrofitted specimens showing flexural failure, respectively. [ABSTRACT FROM AUTHOR]

[Display omitted] • ML methods were used to to predict the tensile load capacity and failure mode of GSSC. • ML models yielded a prediction model that exhibits heightened accuracy and increased generalizability. • SHAP and PDP were employed to enhance interpretability of ML models. • Graphic user interface (GUI) platform was developed to facilitate the application of ML. • An equation for the bond strength between grouting materials and rebar addressing construction defects was developed by GP algorithm. Grouted splice sleeve connection (GSSC) is an important connection technology in prefabricated structures, and the tensile load capacity and failure models of GSSC are very important to joint safety. In this study, two data-driven prediction methods (i.e., the machine learning (ML) method, and the threshold method) are proposed to predict the tensile load capacity and failure mode of GSSC. To this end, a database containing 418 existing GSSC experimental data is built. The database is used for eleven ML algorithms (i.e., linear prediction (LP), artificial neural network (ANN), support vector machine (SVM), k-nearest neighbors (KNN), decision tree (DT), random forest (RF), extremely randomized trees (ET), gradient boosting decision tree (GBDT), extreme gradient boosting (XGBoost), light gradient boosting machine (LightGBM), and categorical boosting (CatBoost)) to establish ML models interpreted by shapley additive explanations (SHAP) and partial dependence plot (PDP). Further, the database is applied to the genetic programming (GP) algorithm to generate a simplified equation for the bond strength between rebar and grouting materials, which is the key mechanical parameter for the threshold method. The results show that both of these methods can effectively predict the tensile load capacity and failure mode of GSSC with various common construction defects, and the predictive performance of ML is slightly greater than that of the threshold method. [ABSTRACT FROM AUTHOR]

Abstract Because of the environmental, technical and economic benefits, plant-based (e.g. jute) natural and mineral-based (e.g. basalt) natural fiber reinforced polymer (FRP) composites are considered as alternatives for conventional glass FRP composites. However, the scarcity of data on the long-term durability of natural FRP composites becomes a major barrier for their wider use in different engineering areas. In this work, durability studies were performed to evaluate the effects of water and alkali solutions, and the temperature of their solutions on weight gain, tensile properties and surface morphology of jute and basalt fabric reinforced epoxy composites. In total, four types of composite specimens (i.e. untreated jute fabric/epoxy, alkali-treated jute fabric/epoxy, silane-treated jute fabric/epoxy and untreated basalt fiber/epoxy) were fabricated and exposed to different ageing conditions for 180 days. The water absorption and tensile properties of these four composite specimens were measured and compared. The results showed that in general, the weight gains of the three plant-based natural jute/epoxy specimens (i.e. from 5.0% to 8.5%) were larger than that of the mineral-based natural basalt/epoxy composite (i.e. from 1.1% to 2.2%). Both alkali and silane treatments of jute fiber reduced the water absorption and enhanced the tensile strength of the resulting jute fabric/epoxy composites. For all the four types of composites, increasing exposure temperature of the water and the alkali solutions caused the reduction in their tensile strength. The strength reduction of these four types of composites at alkali solution was larger than the reduction of the corresponding composite at the water solution. In addition, their reduction in tensile strength was more pronounced compared with that in their Young's modulus. Compared with mineral-based basalt/epoxy composites, the untreated, alkali-treated and the silane-treated plant-based jute fabric/epoxy composites showed higher tensile strength reduction retention for the considered ageing conditions. However, the basalt fiber composites had much higher modulus retention. The deterioration of the interfacial properties of these composites at different ageing conditions was confirmed by the SEM observations. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the diagnostic performance of histogram parameters derived from diffusion-weighted imaging (DWI) for differentiating malignant from benign parotid gland tumors compared with that of hotspot region of interest (ROI)-based apparent diffusion coefficient (ADC) measurement.Methods: Our study retrospectively enrolled 60 patients with parotid gland tumors who had undergone DWI scan for pre-treatment evaluation. ADC measurements were performed using hotspot ROI (ADCHS-ROI)-based and histogram-based approach. Histogram parameters included mean (ADCmean), median (ADCmedian), 10th (ADC10), 90th (ADC90) percentiles, skewness and kurtosis of ADC. Mann-Whitney U test, Kruskal-Wallis test with post hoc Dunn-Bonferroni method and receiver operating characteristic (ROC) curve analyses were used for statistical analyses.Results: ADCHS-ROI and ADC histogram parameters showed no significant differences between malignant and benign parotid gland tumors (All Ps > 0.05). Within the sub-group analyses, Warthin’s tumors showed the lowest ADCHS-ROI, ADCmean, ADCmedian, ADC10 and ADC90 value, followed by malignant tumors and pleomorphic adenomas (All Ps < 0.05). ADC10 out-performed ADCHS-ROI in differentiating malignant tumors from pleomorphic adenomas (area under curve, 0.890 vs 0.821; sensitivity, 79.31 vs 82.76%; specificity, 90.91 vs 72.73%; P = 0.016), and improved the diagnostic performance in differentiating malignant tumors from Warthin’s tumors (area under curve, 1.000 vs 0.965; sensitivity, 100.00 vs 90.91%), although the difference was not significant (P = 0.348).Conclusions: ADC histogram analysis, especially ADC10, might be a promising imaging biomarker for characterizing parotid gland tumors. [ABSTRACT FROM AUTHOR]

• The backbone curve model of RC walls was proposed based on genetic programming-based symbolic regression. • Unlike the black-box characteristic of traditional machine learning models, the GP-SR method is more interpretable. • The proposed model was established individually, addressing each failure mode. • Compared to ASCE41-17, the proposed model predicted the characteristic points for the backbone curve better. Backbone curve, as a nonlinear response analysis method, can be used for performance assessment of residual resistance and performance prediction during the preliminary design of structures. In this study, a backbone curve model of reinforced concrete (RC) walls based on Genetic programming-based symbolic regression (GP-SR) was proposed, which can help to quickly evaluate the bearing capacity and seismic performance of RC walls. Unlike the black-box characteristic of traditional machine learning models, the GP-SR method can give explicit computational equations, which are more interpretable and easier to be used by researchers and engineers. Experimental data of 388 existing RC walls were used for feature selection, model training, and comparison with the modeling method of ASCE 41-17 to verify its effectiveness for modeling the backbone curves of RC walls with four failure modes (i.e., flexure, flexure-shear, shear, and shear-sliding). The results showed that the accuracy of the GP-SR model was better than that of the prediction of ASCE 41-17. Overall, the GP-SR model described well the backbone curves of RC walls with various design conditions. [ABSTRACT FROM AUTHOR]

Fiber-reinforced polymer (FRP) composites has been widely used in the retrofitting of earthquake-damaged concrete structures. In literature, the studies on FRP-confined intact concrete columns have been well documented. However, research on FRP-confined damaged concrete columns is relatively rare. Aiming to solve this problem, the confinement performance of basalt FRP (BFRP) on pre-damaged concrete columns was investigated in the present study. In total, twenty-six concrete cylinders were constructed and tested under axial compression. The effects of pre-damage levels and number of BFRP wrapping layers on the compressive performance of the concrete cylinders were investigated. Eighteen plain concrete cylinders were preloaded at three different stress levels (i.e., up to f′ co , 0.9 f′ co and 0.8 f′ co on the descending branch of the axial compressive stress-strain curve of plain concrete, f′ co was compressive strength of plain concrete and was 37.7 MPa here) to represent the moderate, moderately-severe, and severe damage levels, respectively. The thin surface layer of the damaged plain concrete specimens was removed and the damaged concrete specimens were repaired using early strength cement mortar. Then, the cylinders were wrapped with BFRP sheets and retested under axial compression. The experimental results showed that compared with the plain concrete, the ultimate compression strength and axial strain capacities of the pre-damaged concrete were improved by 10–104% and 186–590% respectively after the BFRP confinement. The ultimate compressive strength and the initial elastic modulus of the BFRP-confined concrete tended to reduce with an increase in pre-damage level. Based on the test results, a modified strength expression and a strain expression were developed to predict the compressive behavior of the BFRP-confined concrete (undamaged). Based on the modified strength and strain expressions, a modified stress-strain expression was further proposed for BFRP-confined damaged concrete. This research concludes that BFRP is an effective external confining material for damaged concrete column members after earthquakes. [ABSTRACT FROM AUTHOR]

In reinforced concrete (RC) structures, reinforcement corrosion, concrete carbonization, and chloride ion erosion occur during service life, which deteriorate the seismic structural capacity of the structures. Most researchers have focused on the effect of the reinforcement corrosion on the seismic behavior of RC columns showing flexural behavior. On the other hand, research on the influence of the combined reinforcement corrosion and concrete carbonization on the seismic behavior of in-service RC columns showing shear-flexural behavior has not been performed. The present study evaluates the seismic performance of low-corroded in-service RC columns showing shear failure under cyclic load. Four RC columns with shear-span ratio 2.3 and light transverse reinforcement were obtained from an in-service RC moment frame building constructed in 1987, and quasi-static cyclic tests were conducted to investigate the seismic behavior of these columns. For the test parameters, axial compression force ratios and longitudinal bars arrangements were considered. The test results showed that as the compression force ratio increased, the failure modes of the in-service RC columns shifted from shear-bond failure to shear-compression failure, and the ductility and energy dissipation capacity decreased. The shear strength of the column specimens was evaluated by five existing shear strength models, considering the effect of reinforcement corrosion. Finally, seismic performance of RC short columns with corroded bars was discussed. [ABSTRACT FROM AUTHOR]

• Cyclic behavior of pre-damaged RC columns with deficient lap splice strengthened or retrofitted with UHPC and NSM was investigated. • The seismic performance of RC columns was significantly improved after strengthening or retrofitting with UHPC and NSM. • The design method addressing the pre-damage effect predicts well the flexural strength of RC columns and beams strengthened with UHPC. Reinforced concrete (RC) columns with deficient lap splice details such as short lap splice length and widely spaced stirrups were vulnerable to earthquakes. In the present study, to evaluate the effectiveness of an innovative retrofitting technique using the combination of ultra-high performance concrete (UHPC) and near surface mounted (NSM) technique on the seismic performance of RC columns with deficient lap splices details, cyclic loading tests were performed on four large-sized RC column specimens. Two RC columns were strengthened with UHPC or the combination of UHPC and NSM, and the other two were retrofitted with the combination of UHPC and NSM after the lateral strength decreased to 85% peak strength during the pre-damage cyclic tests. The load–displacement relationship, stiffness degradation, energy dissipation, and residual displacement of RC columns are evaluated. The test results showed that the peak strength and ductility of RC columns with deficient lap splice are significantly improved after strengthening or retrofitting with the combination of UHPC and NSM. The seismic performance of severely damaged RC columns due to deficient lap splice details can still be effectively restored after retrofitting with the combination of UHPC and NSM. Considering the adverse effect of pre-damage, a design method is proposed to predict the flexural capacity of RC columns retrofitting with UHPC or the combination of UHPC and NSM. The proposed method is also applied to predict the flexural capacity of RC beams strengthened with UHPC. The proposed method predicted well the test results of this study and existing tests. [ABSTRACT FROM AUTHOR]

Fiber-reinforced polymers (FRPs) have been widely used for the seismic strengthening of reinforced concrete (RC) structures in seismic regions across the world during the last decades. However, the crack states of concrete inside the strengthened regions are wrapped by FRP sheets and are not visible to inspectors after earthquakes. Aiming to solve this problem, the crack process of FRP-strengthened large-sized RC column under lateral reversed cyclic loading was investigated based on acoustic emission (AE) techniques in the present study. It was found that AE techniques were effective in revealing the crack process of both FRP-strengthened and unstrengthened RC columns. The AE hits analysis revealed that the damage process of the FRP-strengthened column could be divided into four damage levels qualitatively, and the distribution of AE amplitudes had an obvious relationship with the peak displacements of the strengthened column under cyclic loading. The b-value analysis showed that the variation of the crack magnitude during the cyclic test could be reflected effectively by the trend of b-values. The accumulative AE energy exhibited a good correlation with the accumulative hysteretic energy dissipated during the cyclic test for the FRP-strengthened column. Based on fractal theory, a concise but reliable damage index was proposed to predict the damage levels of FRP-strengthened RC columns and the efficiency of the damage index has been verified through the test results. [ABSTRACT FROM AUTHOR]

• The cracking types of FRP-jacketed pre-damaged concrete were analyzed by AE. • The damage stages were defined by the proposed strain energy-based damage index. • Three damage stages were predicted by the fractal theory-based damage index. • RA-AF analysis and Gaussian mixture model revealed the crack evolution. Fiber-reinforced polymer (FRP) composites have been widely used in the retrofitting of concrete columns after earthquakes. However, FRP composites prevent traditional field inspection techniques from observing concrete cracks inside the FRP-retrofitted columns caused by external loading. In the present study, axial compressive loading tests were performed on basalt FRP (BFRP)-repaired pre-damaged cylindrical concrete accompanied by real-time acoustic emission (AE) monitoring. Three damage stages of BFRP-jacketed cylinders were defined based on the proposed strain energy-based damage index and predicted using fractal theory. The conventional RA value-average frequency (RA-AF) analysis and Gaussian mixture model (GMM) analysis effectively revealed the evolution of crack types of BFRP-repaired pre-damaged cylinders. GMM method verified the effectiveness of the RA-AF analysis and provided a better approximation for the classification of crack types. As the pre-damage degree increased, RA value increased and AF value decreased. The shear cracks developed significantly at the severe damage stage in two-layer BFRP-jacketed cylinders. [ABSTRACT FROM AUTHOR]

• Monotonic and repeated axial compressive behavior of damaged concrete prisms repaired by basalt FRP (BFRP) was investigated. • The initial elastic modulus, and the strength at the turning and ultimate states decreased with the increase of initial damage. • Monotonic and repeated stress–strain relationship was proposed for BFRP-repaired concrete prisms considering the adverse effect of pre-damage level. The damaged concrete columns under earthquake can be retrofitted with fiber-reinforced polymer (FRP) and the axial mechanical properties of the strengthened columns can be greatly enhanced. In the present study, monotonic and repeated axial compressive behavior of damaged concrete prisms repaired by basalt FRP (BFRP) was investigated. Pre-damage tests were performed on plain concrete prismatic specimens under three axial compressive loading levels. Then, the damaged specimens were repaired with 1-, 2-, 4-, and 6-layer BFRP composites, followed by monotonic or repeated compression tests. The test results showed that the compressive strength and axial deformation capacities of the damaged prismatic specimens under monotonic compressive loading were improved remarkably after repairing. However, in the stress–strain curves of BFRP-repaired specimens, the initial elastic modulus, and the strength at the turning and ultimate states decreased with the increase of initial damage. Based on the test results of this study and existing literature, the strength and strain at the turning and ultimate states were estimated, and a monotonic stress–strain relationship was proposed for BFRP-repaired concrete prisms considering the adverse effect of pre-damage level. Further, a modified repeated compressive stress–strain model was proposed for BFRP-repaired damaged concrete prisms. The proposed models predicted well the test results. [ABSTRACT FROM AUTHOR]

Conventional solid reinforced concrete (RC) beams were modified to slotted beams for consideration as thermal insulation structural components. The slotted beam consisted of an outer and an inner beam, respectively, with a slot located near the middle of the beam along its width direction for filling thermal insulation material. Flexural and thermal behavior of the slotted beams were investigated. Three RC reference solid beams and six slotted beams were fabricated and tested under four-point bending tests. The test results indicated that the failure mode of both slotted beams and the solid beams was flexural failure. However, the damage process of the slotted beams was different from that of the solid beams at the final loading stage. The moment curvature analysis indicated that the tensile reinforcement ratio of the outer and inner beams had an important effect on the flexural behavior, especially the ductility of the slotted beams. Thermal study indicated that the heat transfer coefficient of the slotted beam was greatly reduced and the thermal inertia factor increased a lot, compared with the solid beam. In addition, FE simulation results showed that a new frame structure using slotted beams exhibited obvious and attractive thermal insulation property. [ABSTRACT FROM AUTHOR]

Background: Target mismatch (ischemic core, mismatch volume and mismatch ratio) in patients with acute ischemic stroke (AIS) highly relies on the automated perfusion analysis software. Purpose: To evaluate the feasibility and accuracy of using the ABC/2 method to rapidly estimate the target mismatch on computed tomography perfusion (CTP) imaging in patients with AIS, using RAPID results as a reference. Material and Methods: In total, 243 patients with anterior circulation AIS who underwent CTP imaging were retrospectively reviewed. Target mismatch associated perfusion parameters were derived from RAPID results and calculated using the ABC/2 method. Paired t -test was used to assess the difference of volumetric parameters between the two methods. The ability of using the ABC/2 method to predict the important cutoff volumetric metrics was also evaluated. Result: There was no significant difference in the volumes of ischemic core (P = 0.068), ischemic area (P = 0.209), and mismatch volume (P = 0.518) between ABC/2 and RAPID. Using RAPID results as reference, the ABC/2 method showed high accuracy for predicting perfusion parameters (70 mL and 90 mL: sensitivity=98.5% and 98.5%, specificity=100% and 100%, positive predictive value [PPV]=100% and 100%, negative predictive value [NPV]=93.8% and 92.9%; 10 mL and 15mL: sensitivity=99.6% and 99.5%, specificity=55.6% and 50.0%, PPV=96.6% and 94.8%, NPV=90.9% and 92.3%; 1.2 and 1.8: sensitivity=99.6% and 94.8%, specificity=75.0% and 96.9%, PPV=98.7% and 99.5%, NPV=90.0% and 73.8%). Conclusion: The ABC/2 method may be a feasible alternative to RAPID for estimation of target mismatch parameters on CTP in patients with AIS. [ABSTRACT FROM AUTHOR]

Objectives: To explore the value of post-treatment fluid-attenuated inversion recovery vascular hyperintensity (FVH) in predicting clinical outcome in patients with acute ischemic stroke (AIS) after endovascular thrombectomy (EVT). Methods: This retrospective study reviewed data from consecutive patients with large vessel occlusion of anterior circulation between July 2017 and February 2021. Together with other variables, status of post-treatment FVH was assessed for each patient. Good outcome was defined as a 3-month modified Rankin Scale score of 0–2. Chi-square test, Fisher's exact test, independent-samples t test, multivariate logistic regression analysis, and receiver operating characteristic analysis were used as appropriate. Results: Among 84 included patients, 48 (57.1%) patients showed post-treatment FVH. Post-treatment FVH significantly correlated with incomplete recanalization (p < 0.05) and low Alberta Stroke Project Early CT Changes Score on post-treatment diffusion-weighted imaging (p < 0.05). Higher incidence of hemorrhage transformation was observed in patients with post-treatment FVH than those without (27.1% vs. 16.7%); however, the difference did not reach significance (p = 0.259). Successful recanalization (odds ratio [OR], 0.024; 95% confidence interval [CI] 0.003–0.194; p < 0.05), lower National Institutes of Health Stroke Scale scores at admission (NIHSSpre) (OR, 1.196; 95% CI, 1.017–1.406; p < 0.05), and no post-treatment FVH (OR, 74.690; 95% CI, 4.624–1206.421; p < 0.05) were found to be independent predictors of good outcomes. Combined models integrating all three independent predictors (recanalization+NIHSSpre+post-treatment FVH) significantly outperformed the combined model without post-treatment FVH (recanalization+NIHSSpre) in predicting clinical outcome (p = 0.004). Conclusions: Post-treatment FVH may be an effective prognostic marker associated with clinical outcome in patients with AIS after EVT. Key Points: • Post-treatment FVH correlates with incomplete recanalization and higher infarct volume. • Post-treatment FVH is independently associated with an unfavorable outcome. • Post-treatment FVH may provide prognostic information in patients with AIS after EVT. [ABSTRACT FROM AUTHOR]

Contrast-enhanced magnetic resonance imaging (CE-MRI) is a pivotal tool for global disease diagnosis and management. Since its clinical availability in 2009, the off-label use of ferumoxytol for ferumoxytol-enhanced MRI (FE-MRI) has significantly reshaped CE-MRI practices. Unlike MRI that is enhanced by gadolinium-based contrast agents, FE-MRI offers advantages such as reduced contrast agent dosage, extended imaging windows, no nephrotoxicity, higher MRI time efficiency and the capability for molecular imaging. As a leading superparamagnetic iron oxide contrast agent, ferumoxytol is heralded as the next generation of contrast agents. This review delineates the pivotal clinical applications and inherent technical superiority of FE-MRI, providing an avant-garde medical-engineering interdisciplinary lens, thus bridging the gap between clinical demands and engineering innovations. Concurrently, we spotlight the emerging imaging themes and new technical breakthroughs. Lastly, we share our own insights on the potential trajectory of FE-MRI, shedding light on its future within the medical imaging realm. [ABSTRACT FROM AUTHOR]

Abstract: A series of novel dithiocarbamate compounds with the chalcone scaffold have been designed and synthesized, and their biological activities were also evaluated as potential antiproliferation and antitubulin polymerization inhibitors. Compound 2n showed the most potent biological activity in vitro, which inhibited the growth of MCF-7 cells with IC50 of 0.04±0.01μM and the polymerization of tubulin with IC50 of 6.8±0.6μM. To understand the tubulin–inhibitor interaction and the selectivity of the most active compound towards tubulin, molecular modeling studies were performed to dock compound 2n into the colchicine binding site, which suggested probable inhibition mechanism. [Copyright &y& Elsevier]

Abstract: Nine 2-arylthiazolidine-4-carboxylic acid derivatives and nine 3-tert-butoxycarbonyl-2-arylthiazolidine-4-carboxylic acid derivatives were synthesized to screen for their antibacterial activities. Compounds 5, 14–18 were first reported. Their chemical structures were clearly determined by 1H NMR, 13C NMR, ESI mass spectra and elemental analyses, coupled with one selected single-crystal structure. All the compounds were assayed for antibacterial activities against two Gram-positive bacterial strains (Bacillus subtilis ATCC 6633 and Staphylococcus aureus ATCC 6538) and two Gram-negative bacterial strains (Escherichia coli ATCC 35218 and Pseudomonas aeruginosa ATCC 13525) by MTT method. Most of the 3-tert-butoxycarbonyl-2-arylthiazolidine-4-carboxylic acid derivatives exhibited better antibacterial activities against the four bacterial strains than relative 2-arylthiazolidine-4-carboxylic acid derivatives. Compound (2RS,4R)-3-(tert-butoxycarbonyl)-2-(5-fluoro-2-hydroxyphenyl)thiazolidine-4-carboxylic acid (14) showed powerful antibacterial activities against P. aeruginosa with IC50 value of 0.195μg/mL, which was superior to the positive controls Penicillin G and Kanamycin B, respectively. On the basis of the biological results, structure–activity relationships were discussed. [Copyright &y& Elsevier]

Purpose: To assess the diagnostic accuracy of using Alberta Stroke Program Early Computed Tomography Score (ASPECTS) on CT perfusion (CTP) map to predict a volumetric target mismatch in patients with acute ischemic stroke (AIS). Methods: Three-hundred and seven AIS patients with an onset time within 24h or unclear onset time who underwent CTP evaluation for large vessel occlusion of anterior circulation were enrolled. CTP ASPECTS was evaluated on cerebral blood flow (CBF) and time-to-maximum (Tmax) colored maps, respectively. Automated perfusion analysis software was used to calculate the volumes of ischemic core (volumeCBF<30%) and tissue at risk (volumeTmax>6s). Target mismatch was defined as volumeCBF< 30%<70ml, volumemismatch≥15ml, and volumeTmax >6s/volume CBF< 30%≥1.8. Spearman correlation and receiver operating characteristic curves were used for statistical analyses. Results: Strong correlations were found between CBF ASPECTS and volumeCBF<30%, and between Tmax ASPECTS and volumeTmax>6s for overall population (ρ=−0.872, −0.757) and late-arriving patients (ρ=−0.900, −0.789). Mismatch ASPECTS moderately correlated with mismatch volume for overall population (ρ=0.498) and late-arriving patients (ρ=0.407). A CBF ASPECTS≥5 optimally predicted an ischemic core volume<70ml in overall population (sensitivity, 94.4%; specificity, 80.4%) and late-arriving patients (sensitivity, 89.5%; specificity, 90.5%). A CBF ASPECTS≥6 combined with a Mismatch ASPECTS≥1 optimally identified a target mismatch in overall population (sensitivity, 84.5%; specificity, 77.0%) and late-arriving patients (sensitivity, 83.7%; specificity, 90.0%). Conclusion: CTP ASPECTS might be useful in predicting target mismatch derived from automated perfusion analysis software, and assisting in patient selection for endovascular therapy. [ABSTRACT FROM AUTHOR]

With global warming, the great changes in the patterns of plant growth have occurred. The conditions in early spring and late autumn have changed the process of vegetation photosynthesis, which are expected to have a significant impact on net primary productivity (NPP) and affect the global carbon cycle. Currently, the seasonal response characteristics of NPP to phenological changes in dryland ecosystems are still not well defined. This article calibrated and analyzed the normalized difference vegetation index (NDVI) time series of Advanced Very-High-Resolution Radiometer (AVHRR) data from 1982 to 2015 in the Loess Plateau, China. The spatial and temporal distributions of vegetation phenology and NPP in the Loess Plateau under semihumid and semiarid conditions were investigated. The seasonal variation in the NPP response to vegetation phenology under the climate change was also analyzed. The results showed that, different from the northern forest, there was distinct spatial heterogeneity in the effect of climate change on the dynamic change in vegetation growth in the Loess Plateau: 1) an advance of the start of the growing season (SOS) and a delay of the end of the growing season (EOS) significantly increased the NPP in spring and autumn, respectively, in the humid southeast; 2) in the arid northwest, the NPP did not significantly increase in spring and autumn but significantly decreased in summer. [ABSTRACT FROM AUTHOR]

• AE hit and amplitude can effectively detect the first occurrence of concrete crack. • Five cracking stages can be determined by the AE hit and crack intensity analysis. • AE can capture the characteristics of the cracking process of FRP-jacketed concrete. Fiber reinforced polymer (FRP) composites have been widely used in strengthening of existing concrete columns. However, the concrete cracks inside the FRP-strengthened columns caused by external loading cannot be observed by traditional field inspection techniques due to the coverage of FRP composites. In the present study, axial compression loading tests were performed on two unjacketed concrete and six BFRP-jacketed concrete cylinders. Acoustic emission (AE) techniques were utilized to monitor the cracking process of concrete specimens. The conventional AE hit and AE amplitude analysis were effective in detecting the first occurrence of concrete crack. The first noticeable concrete crack and final major crack can be detected by the crack intensity analysis. Then, five stages of cracking process of unjacketed concrete and BFRP-jacketed concrete specimens can be determined by a combination of the AE hit analysis and crack intensity analysis. AE analysis revealed that the cracking process of BFRP-jacketed concrete differed from that of unjacketed concrete, due to the presence of BFRP composites: (1) the time range of AE stable developing stage of BFRP-jacketed concrete was longer than that of the unjacketed concrete and the time range increased with an increase in FRP layers; (2) the crack intensity analysis parameters, which are based on AE signal strength, (i.e., severity index (S r) and historic index (H s)) of BFRP-jacketed specimens presented noticeable higher values at the final failure stage; (3) the RA value-average frequency (RA-AF) analysis revealed that the occurrence of shear cracks was delayed in the BFRP-jacketed concrete. The present study demonstrated that AE monitoring can effectively capture the characteristics of the cracking process of FRP-jacketed concrete. [ABSTRACT FROM AUTHOR]

In reinforced concrete (RC) structures, structural members with damage should be repaired before reuse. Unlike existing studies that focus on strengthening of undamaged RC columns, the present study focused on the compressive properties of pre-damaged RC columns repaired with basalt fiber reinforcement polymer (BFRP) composites. Twenty-two circular columns with a relatively large size were tested. The influence of pre-damage levels, number of BFRP layers, and steel rebars on the compressive properties of the repaired RC columns were investigated. The test results showed that repairing with BFRP increased the strength and ultimate strain of the pre-damaged RC columns by 26–142% and 574–1147%, respectively, compared to the plain concrete counterparts. However, the axial stiffness and compressive strength of the repaired pre-damaged RC columns decreased as the pre-damage level increased. Addressing the adverse effect of pre-damage and the contribution of steel rebars, a strength model, ultimate strain model, and stress–strain relationship model were proposed to predict the compressive responses of the BFRP-repaired RC columns. The proposed models predicted well the test results. This study demonstrates that BFRP repairing is effective in enhancing the compressive strength and deformation capacity of damaged RC columns, even though the pre-damage level is severe. [ABSTRACT FROM AUTHOR]

Objectives: To assess the prognostic value of Alberta Stroke Program Early Computed Tomography Score (ASPECTS) on post-treatment diffusion-weighted imaging (DWI) for acute ischemic stroke (AIS) patients after endovascular thrombectomy (EVT) and compare it with that of infarction volume. Methods: Ninety-eight consecutive AIS patients who underwent EVT and post-treatment DWI were retrospectively enrolled. ASPECTS and infarction volume were evaluated based on post-treatment DWI, respectively. Good clinical outcome was defined as modified Rankin Scale score of 0–2 at 90 days. Predictors of good clinical outcome were evaluated using univariate and multivariate logistic regression analysis. Prognostic value of post-treatment DWI ASPECTS and infarction volume were assessed and compared using receiver-operating-characteristic curves and the DeLong method. Results: Favorable outcome was achieved in 62 (63.3%) patients. A strong correlation was found between post-treatment DWI ASPECTS and infarction volume (ρ = −0.847). Due to strong correlation and potential collinearity, two multivariate logistic regression models were respectively developed which included post-treatment DWI ASPECTS or infarction volume. As a result, post-treatment DWI ASPECTS (OR, 2.401; 95%CI, 1.567–3.678; p < 0.001) and infarction volume (OR, 0.982; 95%CI, 0.846–0.998; p = 0.002) were both independent predictors of good clinical outcome. Setting post-treatment DWI ASPECTS ≥ 6 as a cut-off value, optimal performance (AUC = 0.836; sensitivity, 87.1%; specificity, 66.7%) could be obtained in predicting good clinical outcome, which was comparable with that of infarction volume (cut-off volume, ≤ 94.87 ml; AUC = 0.821; sensitivity, 90.3%; specificity, 55.6%). Conclusions: Post-treatment DWI ASPECTS might be a potential surrogate of infarction volume and be effective in predicting the clinical outcome of AIS patients after EVT. Key Points: • Post-treatment DWI ASPECTS correlated significantly with infarction volume. • A post-treatment DWI ASPECTS ≥ 6 best predicts good outcomes for AIS patients after EVT. • Post-treatment DWI ASPECTS has the potential in substituting infarction volume in predicting the clinical outcome of AIS patients. [ABSTRACT FROM AUTHOR]

Seismic analyses of structures typically require the spectrum of the scaled seed accelerogram to be consistent with a specified target spectrum. Peak ground acceleration (PGA) and Arias intensity levels of scaled and matched ground motions are difficult to maintain after spectral matching with existing time-domain methods. An improved method is thus proposed to address these issues by introducing Arias Intensity Fitting (AIF) and PGA correction algorithms. In addition, adaptive relaxation parameters obtained from particle swarm optimization (PSO) are used to improve convergence efficiency. The effectiveness of the proposed method is validated by a comparison of the spectrally matched records with the scaled time series characteristics. Moreover, the proposed method is compared with two existing time-domain spectral matching methods. Results show that the proposed method performs better in generating the acceleration time series compatible with the target spectrum while preserving the nonstationary characteristics of the scaled seed accelerogram. Considerable improvements in the aspects of PGA and Arias intensity consistency between scaled and matched accelerograms are achieved without reducing the spectral matching accuracy. The convergence efficiency of the proposed method is improved with the implementation of adaptive relaxation parameters. • An improved time domain spectral matching method is proposed. • PGA correction and AIF methods are proposed to appropriate intensity measures. • The intensity measures contain Arias intensity and peak ground acceleration. • Adaptive relaxation parameter is applied to improve convergence efficiency. [ABSTRACT FROM AUTHOR]

• Bond strength of GFRP bars increases with the decrease of stirrup spacing. • Stirrups improved the bond strength of D20 GFRP bars more significantly than that of D28 GFRP bars. • The design method addressing the stirrup effect predicts well the bond strength of GFRP bars. Although the bond behavior of fiber-reinforced polymer (FRP) bars with concrete differs from that of steel bars with concrete, limited studies are available on the bond performance between FRP bars and concrete. To investigate the bond performance of glass FRP (GFRP) bars in concrete, lap splice tests were performed on 22 beam specimens. The test parameters included the spacing of stirrups along the bar splice length, bar diameter, loading type, and type of spliced bar. As with the counterpart specimens, five lap splice specimens using steel bars were also tested. All beam specimens using GFRP bars experienced splitting bond failure. The test results showed that the existence of stirrups along the splice length increased the bond strength of GFRP bars, and the bond strength decreased with the increase of stirrup spacing in the GFRP beam specimens. The bond strength contribution by stirrups was more effective in the GFRP beam specimens with a diameter of 20 mm than that of GFRP beam specimens with a diameter of 28 mm. The digital image correlation (DIC) technique was used to investigate the evolution of cracks in the beam specimens that failed by splitting failure. The current design methods and proposed design method were applied to the test results including existing test results, and the proposed design method predicted well the test results. [ABSTRACT FROM AUTHOR]

The occurrence of drought is related to complicated interactions between many factors, such as precipitation, temperature, evapotranspiration and vegetation. In this study, the relationships between drought and precipitation, temperature, vegetation and evapotranspiration were investigated with a random forest (RF), and a new combined drought monitoring index (CDMI) was constructed. The effectiveness of the CDMI in monitoring drought in Shaanxi Province was verified by the in situ 1 ∼ 12-month standardized precipitation index (SPI); relative soil moisture (RSM) and four other commonly used remote sensing drought monitoring indices. The results show that CDMI is more correlated with the SPI and RSM than the four indices. Moreover, the spatial distributions of drought for the CDMI and RSM are similar. Therefore, the CDMI can be used to monitor droughts in Shaanxi Province, and machine learning can explore the relationships between various factors and establish a drought index without knowledge of the causal mechanisms of these factors. [ABSTRACT FROM AUTHOR]

Removal of a toxic anthraquinone dye—Disperse Blue 56 (DB56) by single red mud (RM) coagulation, single ozonation and combined RM coagulation/ozonation (RM/O3) was carried out in laboratory-scale experiments. RM/O3 treatment exhibited more effective in toxicity removal, color removal and chemical oxygen demand (COD) reduction than the other two methods. The effect of several operational parameters, including initial dye concentration, pH value, RM coagulant dose and O3 dose, on color removal and COD reduction was also investigated. Among these factors, pH value had the most important effect. [ABSTRACT FROM AUTHOR]

Ground-motion amplification factors (GMAFs) are applied to characterize amplification of ground motions propagating from bedrock to ground surface, which are required to construct design response spectrum on ground surface in nuclear industry. To estimate GMAFs by ground response analysis (GRA), appropriate ground motions are required as input motions. This study investigates capabilities of amplitude-scaled and spectrum-matched ground motions to estimate mean GMAFs. It reports that amplitude-scaled motions lead to unbiased estimates of the mean GMAFs. Further investigation shows that, a suite of 5 spectrum-matched motions does not introduce significant bias of the mean GMAFs estimation if soil parameter variabilities are not considered in GRA; however, the bias will remarkably increase when soil parameter variabilities are considered. In addition, this study compares capabilities of spectrum-matched motions generated by different methods to estimate the mean GMAFs. Based on research findings in this study, issues concerning ground motions for GMAFs estimation are discussed. [ABSTRACT FROM AUTHOR]

Vegetation phenology is highly sensitive to climate change, and the phenological responses of vegetation to climate factors vary over time and space. Research on the vegetation phenology in different climatic regimes will help clarify the key factors affecting vegetation changes. In this paper, based on a time-series reconstruction of Moderate-Resolution Imaging Spectroradiometer (MODIS) normalized difference vegetation index (NDVI) data using the Savitzky–Golay filtering method, the phenology parameters of vegetation were extracted, and the Spatio-temporal changes from 2001 to 2016 were analyzed. Moreover, the response characteristics of the vegetation phenology to climate changes, such as changes in temperature, precipitation, and sunshine hours, were discussed. The results showed that the responses of vegetation phenology to climatic factors varied within different climatic regimes and that the Spatio-temporal responses were primarily controlled by the local climatic and topographic conditions. The following were the three key findings. (1) The start of the growing season (SOS) has a regular variation with the latitude, and that in the north is later than that in the south. (2) In arid areas in the north, the SOS is mainly affected by the temperature, and the end of the growing season (EOS) is affected by precipitation, while in humid areas in the south, the SOS is mainly affected by precipitation, and the EOS is affected by the temperature. (3) Human activities play an important role in vegetation phenology changes. These findings would help predict and evaluate the stability of different ecosystems. [ABSTRACT FROM AUTHOR]

Background: Diffusion kurtosis imaging (DKI) is a technique based on the theory that the diffusion of water follows non-Gaussian distribution; until now, few studies have explored the usefulness of DKI in differentiating parotid gland tumors. Purpose: To evaluate the potential of DKI in the characterization of parotid gland tumors. Material and Methods: DKI was performed in 40 patients with parotid gland tumors (33 benign, 7 malignant). DKI parameters including apparent diffusion coefficient (Dapp) and apparent kurtosis coefficient (Kapp) were obtained using the DK model and compared. Intraclass correlation coefficient (ICC) was used to evaluate inter-observer agreement of DKI derived parameters. Results: Excellent inter-observer agreements (Dapp, ICC = 0.988; Kapp, ICC = 0.985) were achieved during quantitative measurements. There were no significant differences in Dapp (P = 0.055) and Kapp (P = 0.915) between the benign and malignant groups. In the subgroup analyses, pleomorphic adenomas showed higher Dapp (P < 0.001) and lower Kapp (P = 0.037) than malignant tumors. Combination of Dapp and Kapp showed optimal discriminative value (area under curve [AUC] = 0.913; sensitivity = 88.89%; specificity = 85.71%). Pleomorphic adenomas also showed higher Dapp (P < 0.001) and lower Kapp (P < 0.001) than Warthin's tumors. A combination of Dapp and Kapp showed optimal discriminative value (AUC = 1.000; sensitivity = 100%; specificity = 100%). Warthin's tumors demonstrated higher Kapp than malignant tumors (P < 0.001), while no significant difference was found on Dapp (P = 0.448). The AUC, sensitivity, and specificity of Kapp for discriminating Warthin's tumors from malignant tumors at an optimal threshold of 0.735 were 0.905, 88.89%, and 85.71%, respectively. Conclusion: DKI may be a promising imaging technique for characterizing parotid gland tumors. [ABSTRACT FROM AUTHOR]

Abstract This study determined the first complete mitochondrial genome (mitogenome) of a stonefly, Scopura longa (Plecoptera: Scopuridae), and reconstructed a phylogeny based on two datasets of mitogenomes in eighteen available stoneflies to examine the relationships among Plecoptera. The complete mitogenome of S. longa is a circular molecule of 15,798 bp in size. It contains 13 protein-coding genes (PCGs), 22 transfer RNA genes (tRNAs), two ribosomal RNA genes (rRNAs) and a control region (CR). Most PCGs used standard ATN start codons and TAN stop codons. All tRNAs could be folded as typical cloverleaf secondary structures except tRNA Ser (AGN), with the dihydrouridine (DHU) arm missing. Tandem repeat regions, two potential stem-loop (SL) structures, Poly T structures and G + C-rich regions are detected in the control region. Finally, the phylogenetic relationships among the families within the Arctoperlaria were reconstructed. The topological structures of the two trees were almost identical. The present phylogenetic analysis shows that S. longa belongs to the infraorder Euholognatha. The monophyly of each family is generally well supported based on nucleotide sequences. The Pteronarcyidae is sister to ((Peltoperlidae + Styloperlidae) + (Perlidae + (Perlodidae + Chloroperlidae))). Highlights • First mitogenome in the family Scopuridae is sequenced. • The first mitochondrial phylogenetic analysis of Scopuridae is performed. • Scopuridae is recovered as sister-group of (Capniidae + Nemouridae) by mitochondrial data. [ABSTRACT FROM AUTHOR]

This paper presented a review of 84 confinement strength models developed for predicting the ultimate compressive strength of carbon fiber-reinforced polymer-confined concrete subjected to uniaxial compression. Among these models, 64 design-oriented models and 12 analysis-oriented models were selected and evaluated by a comprehensive database including the experimental results of 1475 carbon fiber-reinforced polymer-confined concrete specimens through three statistical indicators: the mean (μ), the coefficient of determination (R2), and the root mean square error (σ) of the predicted ultimate compressive strength fcc * and the experimental ultimate strength fcc. Based on the results of evaluation, 27 design-oriented models were further considered for reliability assessment and structural reliability analysis. Given the performance of strength predictions and the reliability assessment, it was found that for the design purpose, the 27 design-oriented models are reliable for practical predictions of carbon fiber-reinforced polymer-confined concrete structures subjected to uniaxial compression. [ABSTRACT FROM AUTHOR]

This paper presented a comprehensive assessment of 22 existing stress models and 13 strain models, which were developed for glass fiber reinforced polymer (GFRP)-confined concrete in uniaxial compression. In addition, a reliability evaluation of these stress and strain models was performed. A database including 212 GFRP-confined cylindrical concrete specimens was collected and analyzed to evaluate the performance of these stress and strain models. The accuracy and applicability assessment of these models were carried out by χ2 test and the Pearson correlation coefficient r, and the Monte Carlo–JC method was used by for the reliability assessment. Based on the evaluation, it was found that the unconfined concrete strength fco is the most important parameter which determines the accuracy of these stress and strain models for GFRP-confined concrete. Most stress and strain models used in this study can predict the ultimate axial strength and strain of the GFRP-confined concrete appropriately, although some scattered points exist for some models. In addition, it was found that all these models satisfy the command of reliability even some models are too conservative. Based on the database, unified stress and strain models were proposed showing better applicability. [ABSTRACT FROM AUTHOR]

A new concrete filled FRP tube (CFFT) with inner steel wire mesh (WM), termed as CFFT-WM, is proposed in this paper. Uniaxial compression tests were carried out on 27 CFFT-WM specimens to investigate the compressive behavior of the composite structure. The considered experimental variables are number of GFRP layers (1, 2 and 3 layers) and volumetric ratios of WM (0.31, 0.60 and 0.89%). Their effects on the failure mode, compressive stress–strain response, confinement effectiveness and ratio, and the Poisson ratio of the specimens are discussed. The test results show that GFRP tube and WM increase the ultimate compressive strength, strain and ductility of the concrete remarkably. The increase in strength is proportional to an increase in number of GFRP layer. Specimen with higher WM volumetric ratio corresponds to a lower ultimate axial strain but larger strength. In addition, the presence of WM results in a post-peak response showing more ductile compared with the conventional CFFT. Based on the experimental results, confinement stress and strain models were proposed to predict the ultimate compressive behavior of CFFT-WM confined concrete. [ABSTRACT FROM AUTHOR]

• An efficient early fusion structure is designed to fuse the features of native CTP, CBF, CBV, MTT and Tmax for accurate ischemic stroke prediction. • The attention mechanism is firstly employed into multi-scale convolutional extractor to capture the context information. • Model was evaluated on a real clinical dataset which was collected from multiple stroke centers. • The dataset uses two kinds of follow-up images: Non-contrast CT and MRI DWI. [Display omitted] Background: Acute ischemic stroke is one of the leading death causes. Delineating stoke infarct core in medical images plays a critical role in optimal stroke treatment selection. However, accurate estimation of infarct core still remains challenging because of 1) the large shape and location variation of infarct cores; 2) the complex relationships between perfusion parameters and final tissue outcome. Methods: We develop an encoder-decoder based semantic model, i.e., Ischemic Stroke Prediction Network (ISP-Net), to predict infarct core after thrombolysis treatment on CT perfusion (CTP) maps. Features of native CTP, CBF (Cerebral Blood Flow), CBV (Cerebral Blood Volume), MTT (Mean Transit Time), Tmax are generated and fused with five-path convolutions for comprehensive analysis. A multi-scale atrous convolution (MSAC) block is firstly put forward as the enriched high-level feature extractor in ISP-Net to improve prediction accuracy. A retrospective dataset which is collected from multiple stroke centers is used to evaluate the performance of ISP-Net. The gold standard infarct cores are delineated on the follow-up scans, i.e., non-contrast CT (NCCT) or MRI diffusion-weighted image (DWI). Results: In clinical dataset cross-validation, we achieve mean Dice Similarity Coefficient (DSC) of 0.801, precision of 81.3 % , sensitivity of 79.5 % , specificity of 99.5 % , Area Under Curve (AUC) of 0.721. Our approach yields better outcomes than several advanced deep learning methods, i.e., Deeplab V3, U-Net++, CE-Net, X-Net and Non-local U-Net, demonstrating the promising performance in infarct core prediction. No significant difference of the prediction error is shown for the patients with follow-up NCCT and follow-up DWI (P >0.05). Conclusion: This study provides an approach for fast and accurate stroke infarct core estimation. We anticipate the prediction results of ISP-Net could offer assistance to the physicians in the thrombolysis or thrombectomy therapy selection. [ABSTRACT FROM AUTHOR]