CHinese Acute Tissue-Based Imaging Selection for Lysis In Stroke Tenecteplase II (CHABLIS-T II): rationale and design.

BACKGROUND AND PURPOSE: Tenecteplase (TNK) has demonstrated non-inferiority to alteplase in patients who had an acute ischaemic stroke presenting within 4.5 hours from symptom onset. The trial is aimed to explore the efficacy and safety of TNK in Chinese patients who had an acute ischaemic stroke with large/medium vessel occlusion in an extended time window. METHODS AND DESIGN: Chinese Acute Tissue-Based Imaging Selection for Lysis In Stroke Tenecteplase II (CHABLIS-T II) is a multicentre, prospective, block-randomised, open-label, blinded-endpoint, phase IIb study. Eligible patients are 1:1 randomised into two groups: 0.25 mg/kg TNK versus best medical management (excluding TNK). The safety and efficacy of 0.25 mg/kg TNK are assessed through reperfusion status and presence of symptomatic intracranial haemorrhage (sICH). STUDY OUTCOMES: The primary outcome is major reperfusion without sICH at 24-48 hours after randomisation. Major reperfusion is defined as restoration of blood flow to greater than 50% of the involved ischaemic territory assessed by catheter angiography or repeated perfusion imaging. Secondary outcomes include post-thrombolytic recanalisation, neurological improvements, change in the National Institutes of Health Stroke Scale score, haemorrhagic transformation at 24-48 hours, systematic bleeding at discharge, modified Rankin Scale (mRS) 0-1, mRS 0-2, mRS 5-6, mRS distribution and Barthel index at 90 days. DISCUSSION: CHABLIS-T II will provide important evidence of intravenous thrombolysis with TNK for patients who had an acute stroke in an extended time window.

The benefit of favorable venous outflow profile is mediated through reduced microvascular dysfunction in acute ischemic stroke.

INTRODUCTIONS: Venous outflow (VO) is emerging as a marker of microvascular integrity in acute ischemic stroke. Using hemorrhagic transformation (HT) and infarct growth as mediators, we tested whether a favorable VO profile benefited functional outcome by reducing consequences of microvascular dysfunction. PATIENTS AND METHODS: Patients receiving thrombectomy in three comprehensive stroke centers due to acute anterior circulation occlusion were included. VO was assessed semi-quantitatively by the opacification of ipsilateral vein of Labbé, Trolard and superficial middle cerebral vein. HT was graded on follow-up CT. Infarct growth volume (IGV) was the difference of final infarct volume and baseline core volume. The association of VO and functional independence (90-day modified Rankin Scale ⩽ 2) was examined by logistic regression. Mediation analysis was performed among VO, HT or IGV, and functional outcome in patients with or without recanalization, respectively. RESULTS: In 242 patients analyzed, VO was strongly correlated with functional independence and VO ⩾ 4 was defined favorable. In 175 patients recanalized, favorable VO was associated with a reduced risk of HT (OR = 0.82, 95% CI 0.71-0.95, p = 0.008), which accounted for 13.1% of the association between VO and favorable outcome. In 67 patients without recanalization, favorable VO was associated with decreased IGV (ß = -0.07, 95% CI -0.11 to -0.02, p = 0.007). The association of favorable VO and functional independence was no longer significant (aOR = 4.84, 95% CI 0.87-38.87, p = 0.089) after including IGV in the model, suggesting a complete mediation. DISCUSSION AND CONCLUSION: In patients with acute anterior large vessel occlusion, the clinical benefit of VO may be mediated through reduced microvascular dysfunction.

Tenecteplase thrombolysis for stroke up to 24 hours after onset with perfusion imaging selection: the umbrella phase IIa CHABLIS-T randomised clinical trial.

BACKGROUND: The performance of intravenous tenecteplase in patients who had an acute ischaemic stroke with large/medium vessel occlusion or severe stenosis in an extended time window remains unknown. We investigated the promise of efficacy and safety of different doses of tenecteplase manufactured in China, in patients who had an acute ischaemic stroke with large/medium vessel occlusion beyond 4.5-hour time window. METHODS: The CHinese Acute tissue-Based imaging selection for Lysis In Stroke-Tenecteplase was an investigator-initiated, umbrella phase IIa, open-label, blinded-endpoint, Simon's two-stage randomised clinical trial in 13 centres across mainland China. Participants who had salvageable brain tissue on automated perfusion imaging and presented within 4.5-24 hours from time of last seen well were randomised to receive 0.25 mg/kg tenecteplase or 0.32 mg/kg tenecteplase, both with a bolus infusion over 5-10 s. The primary outcome was proportion of patients with promise of efficacy and safety defined as reaching major reperfusion without symptomatic intracranial haemorrhage at 24-48 hours after thrombolysis. Assessors were blinded to treatment allocation. All participants who received tenecteplase were included in the analysis. RESULTS: A total of 86 patients who had an acute ischaemic stroke identified with anterior large/medium vessel occlusion or severe stenosis were included in this study from November 2019 to December 2021. All of the 86 patients enrolled either received 0.25 mg/kg (n=43) or 0.32 mg/kg (n=43) tenecteplase, and were available for primary outcome analysis. Fourteen out of 43 patients in the 0.25 mg/kg tenecteplase group and 10 out of 43 patients in the 0.32 mg/kg tenecteplase group reached the primary outcome, providing promise of efficacy and safety for both doses based on Simon's two-stage design. DISCUSSION: Among patients with anterior large/medium vessel occlusion and significant penumbral mismatch presented within 4.5-24 hours from time of last seen well, tenecteplase 0.25 mg/kg and 0.32 mg/kg both provided sufficient promise of efficacy and safety. TRIAL REGISTRATION NUMBER: ClinicalTrials.gov Registry (NCT04086147, https://clinicaltrials.gov/ct2/show/NCT04086147).

Extremely Low Contact Resistivity of Bi2Te3-Based Modules Enabled by NiP-Based Alloy Barrier.

Electrode diffusion barrier plays an important role in thermoelectric cooling devices. Compared with p-type Bi0.5Sb1.5Te3, the compatibility between commercial Ni barrier and n-type Bi2Te2.7Se0.3 is a key bottleneck to enhance the performance of Bi2Te3-based cooling devices. This paper proposed a NiP alloy barrier to improve the compatibility with n-type Bi2Te2.7Se0.3, and systemically investigated the contact and interfacial dynamics properties. Due to the low diffusion rate of NiP alloy, the initial interfacial contact resistivity of Bi2Te2.7Se0.3/NiP is as low as 0.90 µΩ cm2, and it further can be depressed below 1.98 µΩ cm2 even after aging at 423 K for 35 days, indicating the superior thermal stability of the NiP barrier layer compared to the commercial Ni barrier layer. Based on the NiP barrier, a 15-pair bismuth telluride device is prepared and a high cooling temperature difference of 71.5 K at a hot-side temperature of 304 K is achieved, which proves the practical applications potential of NiP barrier for Bi2Te3-based modules.

Predictors of hemodynamic instability during and persistent after carotid artery stenting.

OBJECTIVES: The risk factors for post-carotid artery stenting severe hemodynamic instability remain elusive. This study aimed to identify the predictors of severe hemodynamic instability during and persisted after carotid artery stenting. MATERIALS AND METHODS: Consecutive patients who underwent carotid artery stenting for extracranial carotid artery stenosis at a single-center between September 2018 and July 2021 were retrospectively assessed. The predictive factors of severe hemodynamic instability intraoperation and post-operation were analyzed. RESULTS: Among the 139 patients included, 63 experienced severe hemodynamic instability, with 45 and 18 cases occurring intra and postoperatively, respectively. Persistent was observed in 21 patients. Smoke exposure (odds ratio [OR], 2.38; p=0.039), carotid bifurcation stenosis (OR, 0.91; p=0.018), and large-diameter balloon (>4 mm) dilatation (OR, 11.95; p<0.001) were identified as independent risk factors for hemodynamic instability at any stage of carotid artery stenting. Intraoperatively, large-diameter balloon (>4 mm) dilatation was associated with an increased risk of hemodynamic instability occurrence (OR, 4.67; p=0.01), whereas general anesthesia (OR, 0.19; p=0.001) and a longer distance from the stenosis to the carotid bifurcation (OR, 0.89; p=0.01) were negatively associated with hemodynamic instability. Furthermore, smoking exposure (OR, 3.73; p=0.03), large diameter balloon dilatation (OR, 6.12; p=0.032), distance from stenosis to bifurcation (OR, 0.85; p=0.047) and long-stent (40 mm) implantation (OR, 0.84 [95% confidence interval, 0.74-0.95]; p=0.007) could independently predict persistent hemodynamic instability. CONCLUSION: Patients with a smoking history, lesions near the carotid bulb, or dilatation using a large-diameter balloon were most likely to suffer severe hemodynamic instability. General anesthesia can protect against severe hemodynamic instability only intraoperatively. Long-term stent implantation may reduce persistent hemodynamic instability.

Influence of Fiber Orientation on the Water and Ions Transportation of Engineered Cementitious Composite (ECC).

An engineered cementitious composite (ECC) belongs to a type of high-performance fiber-reinforced materials. Fiber alignment causes the anisotropy of such materials. Herein, the influence of the fiber orientation on water and ion penetration into an ECC was studied. Fiber alignment was achieved using an extrusion approach. Water absorption, sorptivity, chloride penetration resistance, sulfate attack resistance, and freezing-thawing resistance of specimens with fiber aligned horizontally (AH), vertically (AV), and randomly (R), corresponding to the direction of the exposure surface that was studied. The results showed that fibers oriented perpendicular to the water path delayed water migration into the ECC matrix. The sorptivity was significantly affected by the fiber direction. The sorptivity of the AH specimens was 35% and 13% lower than that of the AV and R specimens, respectively. After 180 days of exposure, the chloride penetration depth of the AH specimens was 5.7 mm, which is 13.6% and 20.8% lower than that of the AV and R specimens, respectively. The sulfate ingress profile indicates that the fiber-matrix interface oriented perpendicular to the penetration path can effectively delay sulfate migration. The fiber orientation also influences the compressive strength gain under immersion conditions (Na2SO4 solution, Na2SO4 + NaCl solution, and water). Compared with the AH and R specimens, the AV specimens are more sensitive to the immersion condition. In contrast, the fiber orientation has no significant effect on ECC specimens under freeze-thaw cycles. These findings indicate that controlling the fiber alignment and orientation in an ECC can improve its durability under certain exposure conditions.

Reperfusion measurements, treatment time, and outcomes in patients receiving endovascular treatment within 24 hours of last known well.

AIMS: The aim of this study was to explore the interaction between reperfusion and treatment time on the outcomes of patients undergoing endovascular treatment presenting within 24 h of last known well, and to compare the predictive ability of different reperfusion measurements on outcomes. METHODS: Eligible patients from a single-center cohort were enrolled in this study. Reperfusion was assessed using reperfusion index (decreased volume of hypoperfusion lesion compared with baseline) measured by repeated perfusion imaging, and modified treatment in cerebral ischemia score measured by digital subtraction angiography, respectively. The interactions between reperfusion measurements and treatment time on outcomes were explored using multivariate-adjusted logistic and linear regression models. The predictive abilities of reperfusion measurements on outcomes were compared using area under the receiver operating characteristic curve (ROC-AUC) and values of R-square. RESULTS: Reperfusion index and treatment time had significant interactions on 3-month modified Rankin Scale (mRS) 0-2 and infarct growth (p for interaction <0.05). Although the AUCs were statistically similar (AUCs of mRS 0-2 prediction, mTICI≥2b:0.63, mTICI≥2c:0.59, reperfusion index≥0.5:0.66, reperfusion index ≥0.9:0.73, P value of any of the two AUCs >0.05), reperfusion index≥0.9 showed the highest R-square values in outcome prediction (R-square values of 3-month mRS 0-2 and infarct growth = 0.21) among all the reperfusion measurements. CONCLUSION: Treatment time mitigated the effect of reperfusion on outcomes of patients receiving endovascular treatment within 24 h of last known well. Reperfusion index≥0.9 might serve as a better proxy of good outcomes compared with other reperfusion measurements.

High Thermoelectric Performance of p-Type Bi0.4Sb1.6Te3+x Synthesized by Plasma-Assisted Ball Milling.

The exploration of new synthesis methods is important for the improvement of the thermoelectric property of a material for the different mechanisms of microstructure fabrication, surface activity modulation, and particle refinement. Herein, we prepared p-Bi2Te3 bulk materials by a simple synthesis method of the plasma-assisted ball milling, which yielded finer nanopowders, higher texture of in-plane direction, and higher efficiency compared to the traditional ball milling, favoring the simultaneous improvement of electrical and thermal properties. When combined with the Te liquid sintering, nano-/microscale hierarchical pores were fabricated and the carrier mobility was also increased, which together resulted in the low lattice thermal conductivity of 0.52 W·m-1·K-1 and the high power factor of 43.4 µW·cm-1·K-2 at 300 K, as well as the ranking ahead zT of 1.4@375 K. Thus, this work demonstrated the advantages of plasma-assisted ball milling in highly efficient synthesis of p-type Bi2Te3 with promising thermoelectric performance, which can also be utilized to prepare other thermoelectric materials.

Optimization of Graphene Nanoplatelets Dispersion and Its Performance in Cement Mortars.

As promising next-generation conducting materials, Graphene Nanoplatelets (GNPs) have been widely used to enhance the mechanical and pressure-sensitive properties of cement-based materials. However, this beneficial effect highly depended on its dispersion. In this study, polyvinyl pyrrolidone (PVP) surfactant, high-speed shear, and ultrasonication were used to disperse GNPs. To fully exert the mechanical and pressure-sensitive properties and enhance the dispersion effect of GNPs in cement-based materials, the dispersing method parameters, including PVP concentration, ultrasonication time, shear time, and rate, were optimized. The dispersion degree of GNPs was evaluated by absorbance. The results show that the optimal dispersion parameters were 10 mg/mL of PVP concentration, 15 min of ultrasonication time, 15 min of shear time, and 8000 revolutions per minute (rpm) of shear rate. In addition, the effect of GNPs dosage (0.05, 0.1, 0.3, 0.5, 0.7, and 1.0 wt%) on the setting time, flowability, and mechanical and pressure-sensitive properties of cement mortar were examined. Results reveal that the optimum dosage of GNPs was found at 1.0 wt%.

Association of time to groin puncture with patient outcome after endovascular therapy stratified by etiology.

Background: Randomized clinical trials and large stroke registries have demonstrated a time-dependent benefit of endovascular treatment (EVT) in patients with acute ischemic stroke (AIS) due to large vessel occlusion (LVO). The aim of this study was to investigate whether this could be applied to different stroke subtypes in a real-world single-center cohort. Materials and methods: Consecutive ischemic stroke patients with LVOs presenting within 24 h after symptom onset were prospectively registered and retrospectively assessed. Baseline multimodal imaging was conducted before EVT. Independent predictors of functional independence [90-day modified Rankin scale (mRS), 0-2] and any incidence of intracranial hemorrhage (ICH) were explored using a stepwise logistic regression model in the entire cohort and in stroke subtypes. Results: From 2015 to 2020, 140 eligible patients received EVT, of whom 59 (42%) were classified as large artery atherosclerosis (LAA)-related. Time from last known normal to groin puncture was identified as an independent predictor for functional independence in patients of cardioembolic (CE) subtype [odds ratio (OR) 0.90 per 10 min; 95% CI 0.82-0.98; P = 0.013] but not in the LAA subtype and the whole cohort. Groin puncture within 6 h after the time of last known normal was associated with a lower risk of any ICH in the whole cohort (OR 0.36, 95% CI 0.17-0.75, P = 0.007). Sensitivity analysis of patients with complete imaging profiles also confirmed the above findings. Besides, compared with patients of the CE subtype, the LAA subtype had a smaller baseline ischemic core volume, a better collateral status, a slower core growth rate, and a numerically smaller final infarct volume. Conclusion: Faster groin puncture has a more pronounced effect on the functional outcome in patients of CE subtype than those of LAA subtype. Reducing time to groin puncture is of great importance in improving the prognosis of patients after EVT, especially those of CE subtype, and reducing the incidence of any ICH in all patients.

A Comparison of Different Endovascular Treatment for Vertebral Artery Origin Stenosis.

OBJECTIVE: To compare the safety and efficacy of stenting with drug-eluting stent (DES), stenting with bare mental stent (BMS), and angioplasty alone with drug-coated balloon (DCB) in patients with symptomatic vertebral artery origin stenosis (VAOS) who did not respond to aggressive medical management. METHODS: We performed a retrospective analysis of consecutive patients with symptomatic VAOS who underwent endovascular treatment between December 2018 and November 2021 at our institution. The main outcome compared were technical success, perioperative complications, residual stenosis, stroke recurrence, progression of residual stenosis, and restenosis. RESULTS: A total of 46 patients were included: 29 were stented with DES, 12 were stented with BMS, and 5 received angioplasty alone with DCB. Technical success was achieved in 100%, 100%, and 60%, respectively (P = 0.008). Residual stenosis was 10.8%, 20.2%, and 51.2%, respectively (P < 0.001). Perioperative complications occurred only in 1 case in the DES group (P = 1.00). During a mean follow-up of 14.1 months, stroke recurrence rate was 6.9%, 16.7%, and 0% respectively (P = 0.73). Absolute progression of residual stenosis was 10.1%, 34.9%, and -8.0%, respectively (P < 0.001). Restenosis rate was 6.9%, 50.0%, and 20.0%, respectively (P = 0.007). CONCLUSIONS: In patients with symptomatic VAOS who did not respond to aggressive medical management, stenting with DES shows superiority in the lowering the restenosis rate compared with stenting with BMS. Angioplasty alone with DCB is associated with the slowest progression of stenosis in spite of moderate residual stenosis.

Behavior of Engineered Cementitious Composites (ECCs) Subjected to Coupled Sustained Flexural Load and Salt Frost.

The performance of engineered cementitious composites (ECCs) under coupled salt freezing and loaded conditions is important for its application on the transportation infrastructure. However, in most of the studies, the specimens were generally loaded prior to the freezing. The influence of sustained load was merely considered. To this end, four sustained deflection levels, i.e., 0%, 10%, 30% and 50% of the deflection at the ultimate flexural strength, and three salt concentrations (1%, 3% and 5%) were applied. Prior to the salt frost resistance test, the fluid absorption of ECC specimens under various conditions were measured. The changes in relative dynamic elastic modulus (RDEM) during the freeze-thaw cycles were captured. The depth and the content profile of free chloride were measured after the coupled sustained load and freezing and thawing cycles. It is shown that 3% NaCl solution leads to the largest deterioration in all cases. There is no visible flaking or damage occurring on the surface. The relationships between locally sustained flexural stress and RDEM loss and also locally sustained flexural stress and free chloride penetration depth were proposed and showed satisfactory results. It is concluded that when ECC is subjected to the FTCs under 1% de-ice salt solution, no depassivation of the steel is expected even under a large deflection level. In terms of 3% and 5% salt solution, the thickness of cover should be no less than 20 mm when a deflection level of 0.5 is applied.

Hemispheric cerebral blood flow predicts outcome in acute small subcortical infarcts.

The association between baseline perfusion measures and clinical outcomes in patients with acute small subcortical infarcts (SSIs) has not been studied in detail. Post-processed acute perfusion CT and follow-up diffusion-weighted imaging of 71 patients with SSIs were accurately co-registered. Relative perfusion values were calculated from the perfusion values of the infarct lesion divided by those of the mirrored contralateral area. The association between perfusion measures with clinical outcomes and the interaction with intravenous thrombolysis were studied. Additionally, the perfusion measures for patients having perfusion CT before and after thrombolysis were compared. Higher contralateral hemispheric cerebral blood flow (CBF) was the only independent predictor of an excellent clinical outcome (modified Rankin Scale of 0-1) at 3 months (OR = 1.3, 95% CI 1.1-1.4, P = 0.001) amongst all the perfusion parameters, and had a significant interaction with thrombolysis (P = 0.04). Patients who had perfusion CT after thrombolysis demonstrated a better perfusion profile (relative CBF ≥1) than those who had perfusion CT before thrombolysis (After:45.5%, Before:21.1%, P = 0.03). This study implies that for patients with SSIs, hemispheric CBF is a predictor of clinical outcome and has an influence on the effect of intravenous thrombolysis.

Association of Admission NIHSS Score with Infarct Core Volume and Target Mismatch of Infarct Core/Penumbra Volume on CT Perfusion in Acute Ischaemic Stroke.

INTRODUCTION: Neurological impairment is associated with collateral status in acute ischaemic stroke (AIS). We aimed to validate the association between admission National Institutes of Health Stroke Scale (aNIHSS) score and infarct core volume (ICV) and target infarct core/penumbra volume mismatch (TMM) on CT perfusion (CTP) in AIS patients. METHODS: Patients with acute middle cerebral artery or internal carotid artery occlusion from 2011 to 2020 were included. All patients underwent pretreatment CTP at admission. ICV and TMM were analyzed with MIStar software on CTP maps. aNIHSS scores and clinical characteristics of patients were obtained from our prospectively recorded stroke database. RESULTS: We recruited 182 patients with a median age of 69.5 years; 85 (63.7%) were male, and the median aNIHSS score was 14. Of those, 149 (81.8%) had an ICV < 70 mL, and 139 (76.3%) had TMM. Lower aNIHSS was associated with an ICV < 70 mL, with an area under the curve (AUC) of 0.74, and TMM with an AUC of 0.76. Among all 15 items of the aNIHSS, the gaze score was the only item independently associated with an ICV < 70 mL (adjusted odds ratio [OR] = 0.42, 95% confidence interval [CI]: 0.22-0.79, p = 0.008) and TMM (adjusted OR = 0.5, 95% CI: 0.28-0.9, p = 0.021). One or both aNIHSS ≤ 16 and gaze score = 0 predicted TMM with a sensitivity of 0.79 and a specificity of 0.62. CONCLUSION: aNIHSS may be a useful tool to predict an ICV < 70 mL and TMM on CTP in AIS patients.

Effect of Nano Silica Particles on Impact Resistance and Durability of Concrete Containing Coal Fly Ash.

In this study, the effect of adding nano-silica (NS) particles on the properties of concrete containing coal fly ash were explored, including the mechanical properties, impact resistance, chloride penetration resistance, and freezing-thawing resistance. The NS particles were added into the concrete at 1%, 2%, 3%, 4%, and 5% of the binder weight. The behavior under an impact load was measured using a drop weight impact method, and the number of blows and impact energy difference was used to assess the impact resistance of the specimens. The durability of the concrete includes its chloride penetration and freezing-thawing resistance; these were calculated based on the chloride diffusion coefficient and relative dynamic elastic modulus (RDEM) of the samples after the freezing-thawing cycles, respectively. The experimental results showed that the addition of NS can considerably improve the mechanical properties of concrete, along with its freezing-thawing resistance and chloride penetration resistance. When NS particles were added at different replacement levels, the compressive, flexural, and splitting tensile strengths of the specimens were increased by 15.5%, 27.3%, and 19%, respectively, as compared with a control concrete. The addition of NS enhanced the impact resistance of the concrete, although the brittleness characteristics of the concrete did not change. When the content of the NS particles was 2%, the number of first crack impacts reached a maximum of 37, 23.3% higher compared with the control concrete. Simultaneously, the chloride penetration resistance and freezing-thawing resistance of the samples increased dramatically. The optimal level of cement replacement by NS in concrete for achieving the best impact resistance and durability was 2-3 wt%. It was found that when the percentage of the NS in the cement paste was excessively high, the improvement from adding NS to the properties of the concrete were reduced, and could even lead to negative impacts on the impact resistance and durability of the concrete.

Sequential tirofiban infusions combined with endovascular treatment may improve outcomes in acute ischemic stroke - a meta-analysis.

In this meta-analysis, we explored whether tirofiban could safely improve outcomes when combined with endovascular therapy in acute ischemic stroke with large vessel occlusion. We searched the PubMed, EMBASE, Web of Science, and The Cochrane Library databases from January 2000 to October 2019 for relevant RCTs/non-RCTs. A total of 13 trials involving 2584 patients, of whom 893 (34.5%) received tirofiban, were ultimately included in the meta-analysis. The results suggested that tirofiban improved patient independence at 90 days (51.2% vs 42.4%; OR 1.26; p =0.02) without increasing the risk of symptomatic intracranial hemorrhage (OR 1.01; p =0.96) or mortality (OR 0.86; p =0.09). There was no association between the use of tirofiban and recanalization rate (OR 1.35; p =0.11). Subgroup analysis showed that a loading dose followed by maintenance doses, but not a single dose, of tirofiban increased favorable 90-day functional outcomes (OR 1.49; p =0.0008). Moreover, low maintenance doses may be more effective than high maintenance doses (OR 1.41; p =0.02). These results suggest that adjunctive tirofiban treatment administered as a loading dose followed by low-dose maintenance may improve functional outcomes of endovascular therapy in acute ischemic stroke.

Comparison of methods between CT perfusion source images and CT angiography in collateral flow assessment.

BACKGROUND: The methods used for grading leptomeningeal collateral flow (LMF) on single-phase computed tomography angiography (CTA) are heterogeneous and limited by temporal resolution. PURPOSE: To compare the reliability of relative filling time delay (rFTD) on CT perfusion source images (CTP-SI) and the currently used single-phase CTA collateral assessment methods and evaluate their ability to predict clinical outcomes in acute ischemic stroke patients. MATERIAL AND METHODS: We analyzed consecutive middle cerebral artery or internal carotid artery occlusion patients who received multimodal CT before treatment and within 12 h of stroke symptom onset from October 2015 to December 2018. Patients were dichotomized using the 90-day mRS into good (0-1) versus adverse (2-6) outcomes. CTP-SI was used to identify the rFTD score. CTA images were reconstructed to assess collateral status using the collateral score (Cs) and region leptomeningeal collateral score (rLMCs). Two observers independently assessed images. RESULTS: The baseline characteristics (n = 54) were median age of 67 years and 68.5% of the participants were men. The baseline median NIHSS was 14. Good clinical outcomes were observed in 19 (35.2%) patients. The k value was higher for rFTDs (k = 0.779, P < 0.001) than Cs (k = 0.666, P < 0.001) and rLMCs (k = 0.763, P < 0.001). Higher rFTDs were correlated with lower rLMCs (Spearman's rho -0.68, P < 0.001) and Cs (rho -0.66, P < 0.001). In multivariate logistic regression, rFTD was associated with functional outcomes (P = 0.044). CONCLUSION: The rFTDs method is comparable to single-phase CTA-based assessments in assessing LMFs in acute ischemic stroke patients. Higher rFTDs is independently associated with adverse long-term functional outcomes.

A Feasibility Study of Low Cement Content Foamed Concrete Using High Volume of Waste Lime Mud and Fly Ash for Road Embankment.

This paper aims to study the feasibility of low cement content foamed concrete using waste lime mud (LM) and fly ash (FA) as mineral additives. The LM/FA ratio was first optimized based on the compressive strength. Isothermal calorimetry test, ESEM, and XRD were used to investigate the role of LM during hydration. Afterward, the optimized LM/FA ratio (1/5) was used to design foamed concrete with various wet densities (600, 700, 800 and 900 kg/m3) and LM-FA dosages (0%, 50%, 60%, 70% and 80%). Flowability measurements and mechanical measurements including compressive strength, flexural strength, splitting strength, elastic modulus, and California bearing ratio were conducted. The results show that the foamed concretes have excellent workability and stability with flowability within 170 and 190 mm. The high alkalinity of LM accelerated the hydration of FA, thereby increasing the early strength. The significant power functions were fitted for the relationships between flexural/splitting and compressive strength with all correlation coefficients (R2) larger with 0.95. The mechanical properties of the foamed concrete increased with the density increasing or LM-FA dosage decreasing. The compressive strength, tensile strength, CBR of all prepared foamed concretes were higher than the minimum requirements of 0.8 and 0.15 MPa and 8%, respectively in the standard.

Fracture Models and Effect of Fibers on Fracture Properties of Cementitious Composites-A Review.

Cementitious composites have good ductility and pseudo-crack control. However, in practical applications of these composites, the external load and environmental erosion eventually form a large crack in the matrix, resulting in matrix fracture. The fracture of cementitious composite materials causes not only structural insufficiency, but also economic losses associated with the maintenance and reinforcement of cementitious composite components. Therefore, it is necessary to study the fracture properties of cementitious composites for preventing the fracture of the matrix. In this paper, a multi-crack cracking model, fictitious crack model, crack band model, pseudo-strain hardening model, and double-K fracture model for cementitious composites are presented, and their advantages and disadvantages are analyzed. The multi-crack cracking model can determine the optimal mixing amount of fibers in the matrix. The fictitious crack model and crack band model are stress softening models describing the cohesion in the fracture process area. The pseudo-strain hardening model is mainly applied to ductile materials. The double-K fracture model mainly describes the fracture process of concrete. Additionally, the effects of polyvinyl alcohol (PVA) fibers and steel fibers (SFs) on the fracture properties of the matrix are analyzed. The fracture properties of cementitious composite can be greatly improved by adding 1.5-2% PVA fiber or 4% steel fiber (SF). The fracture property of cementitious composite can also be improved by adding 1.5% steel fiber and 1% PVA fiber. However, there are many problems to be solved for the application of cementitious composites in actual engineering. Therefore, further research is needed to solve the fracture problems frequently encountered in engineering.