Life Cycle Assessment and Impact Correlation Analysis of Fly Ash Geopolymer Concrete.

Geopolymer concrete (GPC) has drawn widespread attention as a universally accepted ideal green material to improve environmental conditions in recent years. The present study systematically quantifies and compares the environmental impact of fly ash GPC and ordinary Portland cement (OPC) concrete under different strength grades by conducting life cycle assessment (LCA). The alkali activator solution to fly ash ratio (S/F), sodium hydroxide concentration (CNaOH), and sodium silicate to sodium hydroxide ratio (SS/SH) were further used as three key parameters to consider their sensitivity to strength and CO2 emissions. The correlation and influence rules were analyzed by Multivariate Analysis of Variance (MANOVA) and Gray Relational Analysis (GRA). The results indicated that the CO2 emission of GPC can be reduced by 62.73%, and the correlation between CO2 emission and compressive strength is not significant for GPC. The degree of influence of the three factors on the compressive strength is CNaOH (66.5%) > SS/SH (20.7%) > S/F (9%) and on CO2 emissions is S/F (87.2%) > SS/SH (10.3%) > CNaOH (2.4%). Fly ash GPC effectively controls the environmental deterioration without compromising its compressive strength; in fact, it even in favor.

Assessment of left ventricular segmental function after autologous bone marrow stem cells transplantation in patients with acute myocardial infarction by tissue tracking and strain imaging.

BACKGROUND: Emerging evidence suggests that stem cells can be used to improve cardiac function in patients after acute myocardial infarction. In this randomized trial, we aimed to use Doppler tissue tracking and strain imaging to assess left ventricular segmental function after intracoronary transfer of autologous bone-marrow stem cells (BMCs) for 6 months' follow up. METHODS: Twenty patients with acute myocardial infarction and anterior descending coronary artery occlusion proven by angiography were [corrected] randomized into intracoronary injection of bone-marrow cell (treated, n = 9) or diluted serum (control, n = 11) groups. GE vivid 7 and Q-analyze software were used to perform echocardiogram in both groups 1 week, 3 months and 6 months after treatment. Three apical views of tissue Doppler imaging were acquired to measure peak systolic displacement (Ds) and peak systolic strain (epsilonpeak) from 12 segments of LV walls. Left ventricular ejection fraction (LVEF), end-diastolic volume (EDV) and end-systolic volume (ESV) were obtained by Simposon's biplane method. RESULTS: (1) 3 months later, Ds and epsilonpeak over the infract-related region clearly increased in the BMCs group [Ds: (4.49 +/- 2.71) mm vs (7.56 +/- 2.95) mm, P < 0.01; epsilonpeak: (-13.40 +/- 6.00)% vs (-17.06 +/- 6.05)%, P < 0.01], but not in the control group [Ds: (4.74 +/- 2.67) mm vs (5.01 +/- 3.23) mm, P > 0.05; epsilonpeak: (-13.84 +/- 6.05)% vs (-15.04 +/- 6.75)%, P > 0.05]. At the same time, Ds over the normal region also increased, but the Ds enhancement was markedly higher in the BMCs group than that in the control group [(3.21 +/- 3.17) mm vs (0.76 +/- 1.94) mm, P < 0.01]. Parameters remained steady from the 3rd to 6th month in either group (P > 0.05). (2) LVEF in treated and control groups were almost the same at baseline (1st week after PCI) [(53.37 +/- 8.92)% vs (53.51 +/- 5.84)%, P > 0.05]. But 6 months later, LVEF in the BMCs group were clearly higher than that in the control group [(59.33 +/- 12.91)% vs (50.30 +/- 8.30)%, P < 0.05]. (3) There were no evident difference in EDV or ESV between two groups at baseline [EDV: (113.74 +/- 23.24) ml vs (129.94 +/- 32.72) ml, P > 0.05; ESV: (57.12 +/- 18.66) ml vs (62.09 +/- 17.68) ml, P > 0.05]. Three months later, EDV and ESV in the control group were markedly greater than those in the BMCs group [EDV: (154.89 +/- 46.34) ml vs (104.85 +/- 33.21) ml, P < 0.05; ESV: (82.91 +/- 35.79) ml vs (49.54 +/- 23.32) ml, P < 0.05]. But EDV and ESV did not change much from 3rd to 6th month in either group (P > 0.05). CONCLUSIONS: Emergency transplantation of autologous BMCs in patients with acute myocardial infarction helps to improve global and regional contractility and attenuate post-infarction left ventricular remodeling. Tissue tracking and strain imaging provide quick, simple and noninvasive methods for quantifying left ventricular segmental function in humans.

[Value of low dose dobutamine real-time myocardial contrast echocardiography in the assessment of coronary artery disease].

OBJECTIVE: To evaluate the value of quantitative real-time myocardial contrast echocardiography (RT-MCE) combined with low dose dobutamine stress test in the detection of coronary artery disease (CAD), and to assess the contribution of collateral blood flow (CBF) to myocardial perfusion. METHODS: Twenty-six hospitalized patients referred for coronary angiography and subsequent revascularization underwent routine echocardiography, RT-MCE at baseline and after low dose dobutamine administration. The images of RT-MCE were analyzed quantitatively from microbubble replenishment curves for myocardial perfusion and its reserve by using the QLab software. RESULTS: At baseline, both beta and A x beta (but not A) were decreased with the increase of severity of coronary stenosis (P < 0.01). Under dobutamine stress, A, beta and A x beta values were decreased with the increase of severity of coronary stenosis (P < 0.01), Graded decreasing in the reserves of A, beta and A x beta were observed with increasing coronary stenosis severity (P < 0.01). Furthermore, significant differences in beta, A x beta, and WMS were observed between segments with CBF and those without. CONCLUSION: Quantitative RT-MCE in conjunction with dobutamine stress can be used as a sensitive measure to identify and stratify CAD as well as to assess the contribution of collateral blood flow.