Response of reinforced mortar‑less interlocking brick wall under seismic loading

Mortar-less construction with interlocking bricks has many advantages, such as improved construction efficiency and relatively low requirements on labour skills. Nevertheless, the seismic performance of interlocking brick structures is not well understood yet. In this paper, laboratory tests and numerical modelling are carried out to investigate the seismic behaviour of interlocking brick walls. Laboratory shaking table tests are performed on a scaled reinforced mortar-less interlocking brick wall. The response and damage modes under in-plane seismic loading are investigated. A detailed numerical model is then generated and validated with the laboratory testing data. Unlike the conventional masonry wall that diagonal shear damage governs the failure, the interlocking brick wall exhibits rocking responses, whose damage is mainly at the two bottom corners of the wall. Full-scale interlocking brick walls are then modelled and compared with conventional concrete masonry unit (CMU) walls bonded by mortar. Comparisons are made between the seismic resistances and damage modes of the two walls. The influences of ground motion intensities, vertical components of seismic excitations and different seismic time histories on the seismic behaviour of the interlocking brick wall are examined. It is found that the interlocking brick wall has a higher seismic resistance capacity than the conventional CMU wall. Inter-brick friction is the main energy dissipation mechanism in the interlocking brick wall. Because of the rocking response, vertical component of the ground motion significantly influences the damage of interlocking brick wall. The interlocking brick wall is insensitive to velocity pulses of ground motions due to its relatively high natural frequency

A novel three-dimensional and tissue Doppler echocardiographic index for diagnosing and prognosticating heart failure with preserved ejection fraction

Introduction: The diagnosis of heart failure with preserved ejection fraction (HFpEF) remains challenging. In this study, a novel echocardiography index based on three-dimensional and tissue Doppler echocardiography for diagnosing and estimating prognosis in HFpEF. Materials and Methods: Patients with symptoms and/or signs of heart failure and normal left ventricular ejection fraction (LVEF ≥50%) who underwent right heart catheterization were screened. Patients were divided based on pulmonary capillary wedge pressure (PCWP) of ≥15 mmHg and PCWP <15 mmHg. A diagnosis of HFpEF was confirmed by PCWP of ≥15 mmHg according to ESC guidelines. A novel index was calculated by the ratio between stroke volume standardized to body surface area (SVI) and tissue Doppler mitral annulus systolic peak velocity S' (SVI/S'). Its diagnostic and prognostic values were determined. Results: A total of 104 patients (mean age 64 ± 12 years) were included. Of these, 63 had PCWP ≥15 mmHg and 41 patients had PCWP <15 mmHg. Compared to the PCWP <15 mmHg group, the ≥15 mmHg group had a significantly lower SVI/S' (P < 0.001). Logistic regression showed that SVI/S' was associated with high PCWP measured invasively. The SVI/S' had an area under the curve of 0.761 for diagnosing classifying between PCWP ≥15 mmHg and <15 mmHg. Kaplan–Meier analysis showed that the lower SVI/S' group showed a poorer prognosis. Conclusions: SVI/S' is a non-invasive index calculated by three-dimensional and tissue Doppler echocardiography. It is a surrogate measure of PCWP and can be used to diagnose and determine prognosis in HFpEF

Effects of guanidinoacetic acid supplementation on liver and breast muscle fat deposition, lipid levels, and lipid metabolism-related gene expression in ducks

Exogenous supplementation of guanidinoacetic acid can mechanistically regulate the energy distribution in muscle cells. This study aimed to investigate the effects of guanidinoacetic acid supplementation on liver and breast muscle fat deposition, lipid levels, and lipid metabolism-related gene expression in ducks. We randomly divided 480 42 days-old female Jiaji ducks into four groups with six replicates and 20 ducks for each replicate. The control group was fed the basal diet, and the experimental groups were fed the basal diet with 400, 600, and 800 mg/kg (GA400, GA600, and GA800) guanidinoacetic acid, respectively. Compared with the control group, (1) the total cholesterol (p = 0.0262), triglycerides (p = 0.0357), malondialdehyde (p = 0.0452) contents were lower in GA400, GA600 and GA800 in the liver; (2) the total cholesterol (p = 0.0365), triglycerides (p = 0.0459), and malondialdehyde (p = 0.0326) contents in breast muscle were decreased in GA400, GA600 and GA800; (3) the high density lipoprotein (p = 0.0356) and apolipoprotein-A1 (p = 0.0125) contents were increased in GA600 in the liver; (4) the apolipoprotein-A1 contents (p = 0.0489) in breast muscle were higher in GA600 and GA800; (5) the lipoprotein lipase contents (p = 0.0325) in the liver were higher in GA600 and GA800; (6) the malate dehydrogenase contents (p = 0.0269) in breast muscle were lower in GA400, GA600, and GA800; (7) the insulin induced gene 1 (p = 0.0326), fatty acid transport protein 1 (p = 0.0412), and lipoprotein lipase (p = 0.0235) relative expression were higher in GA400, GA600, and GA800 in the liver; (8) the insulin induced gene 1 (p = 0.0269), fatty acid transport protein 1 (p = 0.0234), and lipoprotein lipase (p = 0.0425) relative expression were increased in GA400, GA600, and GA800 in breast muscle. In this study, the optimum dosage of 600 mg/kg guanidinoacetic acid improved the liver and breast muscle fat deposition, lipid levels, and lipid metabolism-related gene expression in ducks

A Novel Three-Dimensional and Tissue Doppler Echocardiographic Index for Diagnosing and Prognosticating Heart Failure With Preserved Ejection Fraction

INTRODUCTION: The diagnosis of heart failure with preserved ejection fraction (HFpEF) remains challenging. In this study, a novel echocardiography index based on three-dimensional and tissue Doppler echocardiography for diagnosing and estimating prognosis in HFpEF. MATERIALS AND METHODS: Patients with symptoms and/or signs of heart failure and normal left ventricular ejection fraction (LVEF ≥50%) who underwent right heart catheterization were screened. Patients were divided based on pulmonary capillary wedge pressure (PCWP) of ≥15 mmHg and PCWP <15 mmHg. A diagnosis of HFpEF was confirmed by PCWP of ≥15 mmHg according to ESC guidelines. A novel index was calculated by the ratio between stroke volume standardized to body surface area (SVI) and tissue Doppler mitral annulus systolic peak velocity S' (SVI/S'). Its diagnostic and prognostic values were determined. RESULTS: A total of 104 patients (mean age 64 ± 12 years) were included. Of these, 63 had PCWP ≥15 mmHg and 41 patients had PCWP <15 mmHg. Compared to the PCWP <15 mmHg group, the ≥15 mmHg group had a significantly lower SVI/S' (P < 0.001). Logistic regression showed that SVI/S' was associated with high PCWP measured invasively. The SVI/S' had an area under the curve of 0.761 for diagnosing classifying between PCWP ≥15 mmHg and <15 mmHg. Kaplan–Meier analysis showed that the lower SVI/S' group showed a poorer prognosis. CONCLUSIONS: SVI/S' is a non-invasive index calculated by three-dimensional and tissue Doppler echocardiography. It is a surrogate measure of PCWP and can be used to diagnose and determine prognosis in HFpEF

Experimental and numerical studies of the shear resistance capacities of interlocking blocks

Interlocking bricks could improve construction efficiency, reduce labour cost, and provide better mechanical performance for masonry structures. Nevertheless, the shear properties of mortar-less interlocking bricks have not been systematically investigated which may impede their wide applications. In this study, the shear performance of a new type of interlocking brick is investigated in detail. Laboratory shear test is firstly conducted to study the damage and shear capacity of mortar-less (dry-stacked) interlocking bricks. Numerical model is then generated with consideration of contact imperfection and validated with test results. Intensive parametric studies are conducted to quantify the influences of material strength, axial pre-compression force, friction coefficients, and contact imperfection at brick interfaces on the shear response of interlocking prisms. The accuracy of existing methods for predicting the shear capacities of shear key by design standard and empirical formula are evaluated. Based on the numerical and laboratory results, an empirical design formula is proposed to predict the shear capacity of the interlocking brick

Identifying a Leading Predictor of Arctic Stratospheric Ozone for April Precipitation in Eastern North America

An analysis of the relationship between changes in Arctic stratospheric ozone (ASO) and precipitation in eastern North America (38°–54°N, 65°–87°W; PENA) was performed using observational and reanalysis data coupled with the Whole Atmosphere Community Climate Model version 4 (WACCM4). We found that March ASO exhibits a strong correlation with PENA in April, indicating that the one-month leading ASO exerts a potentially strong impact on April PENA. Changes in tropospheric circulation over the North Pacific and North America can be influenced by ASO anomalies via stratosphere–troposphere interactions. Increased ASO typically results in the transport of drier, colder air from northwest to eastern North America and suppresses local convective activity by enhancing regional downwelling. These conditions lead to a decrease in regional atmospheric water vapor content (1000–600 hPa). Abnormally high ASO may therefore suppress precipitation, whereas abnormally low ASO serves to enhance precipitation, and the finding is supported by WACCM4 simulations incorporating these ASO anomaly signals. We also present an ASO-based statistical linear model for predicting April PENA. Results confirm that the linear model reproduces April PENA for both training and testing periods, based on March ASO, demonstrating the reliability and stability of this linear model. This study verifies that ASO is a viable predictor for projecting April PENA and thus improving forecasts of regional seasonal precipitation