[Heavy Metal Emissions from Coal-fired Power Plants and Heavy Metal Pollution Characteristics and Health Risks in Surrounding Soils].

The aim of this study was to reveal the influence of heavy metal emissions from the flue gas of coal-fired power plants on the surrounding soil environment. Seven heavy metals, including As, Cd, Cr, Cu, Pb, Hg, and Ni, were detected in the flue gas of six coal-fired power plants in Shijiazhuang, and the heavy metals in the soil surrounding the power plants were analyzed. The source analysis and health risk assessment of the heavy metals were carried out. The results showed that after a series of flue gas pollutant control measures, the emission concentrations of different heavy metals in the flue gas of the coal-fired power plants ranged from 0.11 to 6.32 mg·(MW·h)-1, and Cu, Cr, and Ni were the main pollutants. The total amount of the seven heavy metal elements discharged into the atmosphere by each power plant was 33.56-275.71 kg·a-1. The average contents of Cr, Cu, Pb, Hg, and Ni in the surface soil surrounding the coal-fired power plant were higher than the background values of Hebei soil, and the contents were 1.16-2.32 times higher than the background values. The heavy metal content in the soil around the power plants was proportional to the heavy metal emissions in the flue gas. The heavy metal content in the soil under different wind directions first increased and then decreased gradually with the increase in distance from the power plants. Source analysis showed that coal combustion emissions contributed the most to heavy metals in soil around the power plants (41.4%), followed by industrial emissions (23.6%) and transportation emissions (19.6%). Altogether, human activities played a leading role in soil heavy metal enrichment, accounting for 84.6%. The health risk assessment showed that the overall health risk of metal elements in the soil surrounding the power plant was within acceptable limits.

Differences in the predictive value of red cell distribution width for the mortality of patients with heart failure due to various heart diseases.

BACKGROUND: Increased red blood cell distribution width (RDW) is associated with adverse outcomes in patients with heart failure (HF). The objective of this study was to compare the differences in the predictive value of RDW in patients with HF due to different causes. METHODS: We retrospectively investigated 1,021 HF patients from October 2009 to December 2011 at Fuwai Hospital (Beijing, China). HF in these patients was caused by three diseases; coronary heart disease (CHD), dilated cardiomyopathy (DCM) and valvular heart disease (VHD). Patients were followed-up for 21 ± 9 months. RESULTS: The RDW, mortality and survival duration were significantly different among the three groups. Kaplan-Meier analysis showed that the cumulative survival decreased significantly with increased RDW in patients with HF caused by CHD and DCM, but not in those with HF patients caused by VHD. In a multivariable model, RDW was identified as an independent predictor for the mortality of HF patients with CHD (P < 0.001, HR 1.315, 95% CI 1.122-1.543). The group with higher N-terminal pro-brain natriuretic peptide (NT-proBNP) and higher RDW than median had the lowest cumulative survival in patients with HF due to CHD, but not in patients with HF due to DCM. CONCLUSIONS: RDW is a prognostic indicator for patients with HF caused by CHD and DCM; thus, RDW adds important information to NT-proBNP in CHD caused HF patients.

[The effects of different welding wires on the mechanical properties of laser welding joints].

PURPOSE: To evaluate the mechanical properties and microstructure of laser-welded joints with different welding wires for clinical use of welding wire. METHODS: The standard tensile test and three-point bending test rods were made from Co-Cr and Ni-Cr alloy, and were laser-welded with different welding wire (commercially welding wire and casting wire). Then the tensile rods were tested for the ultimate tensile strength (UTS), and the bending rods for the ultimate bending strength (UBS). The results was analyzed by one-way ANOVA. The tensile fracture surface were examined by scanning electron microscopy (SEM). Metallurgical analysis were also performed on polished longitudinal sectioned samples. RESULTS: For Co-Cr alloy, the UTS of casting wire group and commercially welding wire group was respectively (606.40+/-82.53)MPa and (693.61+/-47.68)MPa; the UBS was respectively (997.95+/-88.89)MPa and (1160.76+/-91.59)MPa. ANOVA showed a significant difference of UTS and UBS between the two groups at the 0.05 level (P<0.05). For Ni-Cr alloy, the UTS of casting wire group and commercially welding wire group was respectively (558.14+/-46.75)MPa and (582.32+/-35.43)MPa; the UBS was respectively (1084.75+/-46.02)MPa and (1078.29+/-36.25)MPa. There was no significant difference between the two groups (P>0.05). SEM and metallurgical examination showed the welded zone exhibiting more cracks in the casting wire group than in the commercially welding wire group. CONCLUSION: It would be advisable to work with commercially welding wire for the joints that need better strength.

[Effect of irradiation power on the mechanical properties of laser-welded titanium joints.].

PURPOSE: To make an clinical implication for the use of laser welding pure titanium,this study investigate the effect of irradiation power on the mechanical properties of laser-welded joints. METHODS: The pure titanium tensile test and three-point bending test rods were laser-welded with different irradiation power. Then the tensile rods were tested for the ultimate tensile strength (UTS), and the bending rods for the ultimate bending strength (UBS). The tensile fracture surface was examined by scanning electron microscopy (SEM). Metallurgical analysis was also performed on polished longitudinal sectioned samples. RESULTS: A small portion of the central area in group 1.4 kW was not joined. ANOVA showed no significant difference of OTS and VBS between group 1.6 kW and group 1.8 kW at the 0.05 level. SEM examination and metallurgical analysis showed that there were defects such as pores and cracks in the welding zone; and as the irradiation power increased, there were more pores and cracks. CONCLUSION: The increase in laser irradiation power cannot increase melting depth significantly.

[An experimental study on laser-welded dissimilar alloys in dentistry.].

PURPOSE: This study evaluated the mechanical properties and microstructure of the joints of laser-welded dissimilar alloys usually used in clinical nowadays. METHODS: The dissimilar alloys for Co-Cr alloy,Ni-Cr alloy and pure titanium were laser-welded. The joints were tested for the ultimate tensile strength (UTS) and the ultimate bending strength (UBS). The tensile fracture surfaces were examined by scanning electron microscopy (SEM). Metallurgical analysis was also performed on polished longitudinal sectioned samples. RESULTS: Laser-welded dissimilar alloys between Co-Cr and Ni-Cr alloy can yield satisfactory mechanical properties, and there was no significant difference of UTS and UBS between Co-Cr welding wire group and Ni-Cr welding wire group (P>0.05). The laser-welded joints for dissimilar metal of pure titanium and Co-Cr,pure titanium and Ni-Cr, showed more brittle characteristics and severe defects (pores and cracks). CONCLUSIONS: With Co-Cr or Ni-Cr welding wire, the laser-welded dissimilar alloys of Co-Cr alloy and Ni-Cr alloy can yield satisfactory joints. But pure titanium and Co-Cr alloy, pure titanium and Ni-Cr alloy cannot be directly melted together.

[Effect of laser irradiation power on the mechanical properties of Co-Cr and Ni-Cr laser-welded joints.].

PURPOSE: To investigate the effect of different irradiation power on the mechanical properties of laser-welded joints. METHODS: The standard tensile test and three-point bending test rods made from Co-Cr and Ni-Cr alloy were laser-welded with different irradiation powers. Then the tensile rods were tested for the ultimate tensile strength (UTS), and the bending rods for the ultimate bending strength (UBS). The tensile fracture surface was examined by scanning electron microscopy (SEM). Metallurgical analysis and microhardness test were also performed on polished longitudinal sectioned samples. RESULTS: For Co-Cr alloy, greater irradiation power resulted in greater UTS, minor UBS. For Ni-Cr alloy, there was no significant difference of UTS and UBS between the four groups. SEM and metallurgical examination showed that the welded zone exhibited more gas pores and cracks as the irradiation power increased. Microhardness test showed that hardness increased toward the center of the welded zone and as the irradiation power increased, the range of hardness increased was expanded. CONCLUSION: The optimal laser irradiation power was the key to achieved superior mechanical properties joints.