Dispersion and Lubrication of Zinc Stearate in Polypropylene/Sodium 4-[(4-chlorobenzoyl) amino] Benzoate Nucleating Agent Composite.

Zinc stearate (Znst) was physically blended with the sodium 4-[(4 chlorobenzoyl) amino] benzoate (SCAB) to obtain the SCAB-Znst composite nucleating agent. Znst was used to improve the dispersion property of SCAB and exert a lubricating effect on the PP matrix. The scanning electron microscopy and the fracture surface morphology of the PP/SCAB composite illustrated that the addition of Znst greatly reduced the aggregation phenomenon of SCAB in the PP matrix. The result of the rotary rheometer indicated that Znst exhibits internal lubrication in PP. The DSC result illustrated that the crystallization properties of PP were improved. Compared with pure PP, the Tc of the PP/SCAB composite increased by 1.44 °C (PP/Znst), 13.48 °C (PP/SCAB), and 14.96 °C (PP/SCAB-Znst), respectively. The flexural strength of pure PP, PP/SCAB, and PP/SCAB-Znst were 35.8 MPa, 38.8 MPa, and 40.6 MPa, respectively. The tensile strength of the PP/SCAB and PP/SCAB-Znst reached the values of 39.8 MPa and 42.9 MPa, respectively, compared with pure PP (34.1 MPa). The results demonstrated that Znst can promote the dispersion of SCAB in the PP matrix while exerting a lubricating effect, which enabled the enhancement of the crystalline and mechanical properties of PP.

Lattice Matching and Microstructure of the Aromatic Amide Fatty Acid Salts Nucleating Agent on the Crystallization Behavior of Recycled Polyethylene Terephthalate.

To solve the decrease in the crystallization, mechanical and thermal properties of recycled polyethylene terephthalate (rPET) during mechanical recycling, the aromatic amide fatty acid salt nucleating agents Na-4-ClBeAmBe, Na-4-ClBeAmGl and Na-4-ClAcAmBe were synthesized and the rPET/nucleating agent blend was prepared by melting blending. The molecular structure, the thermal stability, the microstructure and the crystal structure of the nucleating agent were characterized in detail. The differential scanning calorimetry (DSC) result indicated that the addition of the nucleating agent improved the crystallization temperature and accelerated the crystallization rate of the rPET. The nucleation efficiencies (NE) of the Na-4-ClBeAmBe, Na-4-ClBeAmGl and Na-4-ClAcAmBe were increased by 87.2%, 87.3% and 41.7% compared with rPET which indicated that Na-4-ClBeAmBe and Na-4-ClBeAmGl, with their long-strip microstructures, were more conducive to promoting the nucleation of rPET. The equilibrium melting points (Tm0) of rPET/Na-4-ClBeAmBe, rPET/Na-4-ClBeAmGl and rPET/Na-4-ClAcAmBe were increased by 11.7 °C, 18.6 °C and 1.9 °C compared with rPET, which illustrated that the lower mismatch rate between rPET and Na-4-ClBeAmGl (0.8% in b-axis) caused Na-4-ClBeAmGl to be the most capable in inducing the epitaxial crystallization and orient growth along the b-axis direction of the rPET. The small angle X-ray diffraction (SAXS) result proved this conclusion. Meanwhile, the addition of Na-4-ClBeAmGl caused the clearest increase in the rPET of its flexural strength and heat-distortion temperature (HDT) at 20.4% and 46.7%.

Coronary computed tomography angiography study on the relationship between the Ramus Intermedius and Atherosclerosis in the bifurcation of the left main coronary artery.

OBJECTIVE: This study aimed to explore the relationship between the ramus intermedius (RI) and atherosclerosis in the bifurcation of the left coronary artery (LCA). METHODS: Screening patients who underwent CCTA from January to September 2021, 100 patients with RI (RI group) and 100 patients without RI (no-RI group) were randomly enrolled, Evaluation of RI distribution characteristics and left main coronary artery(LM),Left anterior descending branch(LAD),left circumflex branch(LCX) proximal segment plaque distribution, measurement of LAD-LCX bifurcation angle(∠LAD-LCX),Comparison of the three distribution characteristics with the incidence of plaques in the left main trunk bifurcation area (LM, LAD, LCX) between groups and within the RI group. RESULTS: The difference in the incidence of plaques in the proximal LCX and the LM between the RI group and the no-RI group were not statistically significant (P > 0.05). The incidence of plaques in the proximal LAD in the RI group was significantly higher than that in the non-RI group (77% versus 53%, P < 0.05). However, there was no statistically significant difference between the two groups after PSM. A univariate logistic regression analysis revealed that an RI was a risk factor for plaque formation in the proximal LAD (P < 0.001), and a multivariate logistic regression analysis revealed that an RI was not an independent risk factor for plaque formation in the proximal LAD (P > 0.05). When compared within the RI group, the difference in the incidence of plaques in the proximal segment of LAD, the proximal segment of LCX, and the LM among the different distribution groups of RI was not statistically significant, respectively (P > 0.05). CONCLUSION: RI is not an independent risk factor for atherosclerosis in the left coronary artery bifurcation zone, but it may indirectly increase the risk of atherosclerosis in the proximal segment of the LAD.

Study on the correlation between false-positive filling defect in LAA CT and LAA structure in patients with atrial fibrillation based on TEE.

OBJECTIVE: This study aims to explore the actual meaning of "false positive filling defect" in left atrial appendage (LAA) computed tomography (CT) in patients with atrial fibrillation (AF), with transesophageal echocardiography (TEE) as the gold standard. METHODS: Patients with AF undergoing cardiac CT angiography and TEE examinations for proposed radiofrequency catheter ablation between October 2020 and October 2021 were selected as the study subjects. Transesophageal echocardiography was taken as the "gold standard," and spontaneous echocardiographic contrast (SEC) and thrombus events were defined as positive events. The CT manifestations were classified into three groups (true positive, false positive, and true negative) to evaluate the differences in left atrium (LA) anterior-posterior diameter (LAAP), LA anterior wall thickness, and LAA orifice long diameter and short diameter, area, and depth between the three groups. RESULTS: (1) There was no statistical difference in LA anterior wall thickness between the three groups (p > .05); there was a statistical difference in LAAP (only) between the true-positive group and the true-negative group (p < .05). (2) There was a statistical difference in LAA orifice long diameter, short diameter, and area between the true-positive group and the true-negative group as well as between the false-positive group and the true-negative group (p < .05). (3) There was a statistical difference in LAA depth between the true-positive group and the false-positive group as well as between the true-positive group and the true-negative group (p < .05). (4) The area under the receiver operator characteristic curve (AUC) of LAA depth affecting the LAA thrombus and SEC was 0.863 (confidence interval = 0.718-1.000), the sensitivity was 77.8%, and the specificity was 90.6% for predicting the occurrence of LAA thrombus and SEC in patients with nonvalvular AF (NVAF) and an LAA depth of ≥50.84 mm. CONCLUSIONS: There was a difference in LAA diameter between the TEE-based CT false-positive group and the other groups. A "CT false positive" is an objectively existing state, and CT might be able to identify the LAA hemodynamic disorder earlier than TEE. Furthermore, a CT + TEE combined application could more accurately evaluate LAA hemodynamics in patients with AF.

The Comparison of the Diagnostic Value of Left Atrial Pulmonary Vein Single-Phase and Dual-Phase Enhanced CT Scanning for Left Atrial Appendage Thrombosis and SEC in Patients with Atrial Fibrillation.

Objective: The accuracy of left atrial pulmonary vein CT enhanced single-phase and dual-phase scanning in the detection of left atrial appendage (LAA) thrombosis and spontaneous echo contrast (SEC) before radio frequency ablation was compared in atrial fibrillation patients, so as to optimize the scanning scheme. Methods: 78 patients with atrial fibrillation who were admitted to Cangzhou Central Hospital from October 2020 to September 2021 and underwent bilateral enhanced CT scan of left atrial pulmonary vein and transesophageal echocardiography (TEE) examination for planned frequency ablation were selected. TEE results were used as the "gold standard" to compare the diagnostic efficacy of the first phase, second phase, and double-phase comprehensive mode of enhanced left atrial pulmonary vein CT in detecting left atrial thrombosis and SEC. Results: The sensitivity, specificity, positive predictive value, and negative predictive value were 88.9%, 84.1%, 42.1%, and 98.3%, respectively, in the detection of left atrial thrombosis and SEC by the first phase of CT enhanced scan. The sensitivity, specificity, positive predictive value, and negative predictive value were 22.2%, 98.6%, 66.6%, and 90.7%, respectively, in the detection of left atrial thrombosis and SEC by the second phase of CT enhanced scan. The sensitivity, specificity, positive predictive value, and negative predictive value were 88.9%, 84.1%, 42.1%, and 98.3%, respectively, in the detection of left atrial thrombosis and SEC by the double-phase comprehensive mode of CT enhanced scan. There was no statistically significant difference in the accuracy of CT diagnosis of left atrial appendage thrombosis and SEC between the three modes of the first phase, the second phase, and the double-phase comprehensive CT (P > 0.05). The mean effective radiation dose of double-phase enhanced scan was 7.49 ± 1.02 mSv. Conclusion: Single-phase enhanced CT scan of left atrial pulmonary vein can meet clinical requirements and significantly reduce the radiation dose compared with double-phase enhanced CT scan. Therefore, it is recommended as an initial screening examination for patients with atrial fibrillation before radiofrequency ablation.

[Design and Implementation of Heart Sound Detection Device Based on MEMS MIC].

The paper describes how to develop a digital heart sound signal detection device based on high gain MEMS MIC that can accurately collect and store human heart sounds. According to the method of collecting heart sound signal by traditional stethoscope, the system improves the traditional stethoscope, and a composite probe equipped with a MEMS microphone sensor is designed. The MEMS microphone sensor converts the sound pressure signal into a voltage signal, and then amplifies, converts with Sigma Delta, extracts and filters the collected signal. After the heart sound signal is uploaded to the PC, the Empirical Mode Decomposition (EMD) is carried out to reconstruct the signal, and then the Independent Component Analysis (ICA) method is used for blind source separation and finally the heart rate is calculated by autocorrelation analysis. At the end of the paper, a preliminary comparative analysis of the performance of the system was carried out, and the accuracy of the heart sound signal was verified.