Fatigue Characteristics of 7050-T7451 Aluminum Alloy Friction Stir Welding Joints and the Stress Ratio Effect.

The fatigue crack initiation and growth characteristics in 7050-T7451 aluminum alloy butt joints subjected to different stress ratios and owing to friction stir welding (FSW) were investigated using fatigue tests for stress ratios of 0.1, 0.3, and 0.5. The difference between the fatigue crack initiation in the base material (BM) and FSW joints, related to coarse secondary phases, was explored using scanning electron microscopy (SEM). Accordingly, Al23CuFe4, Al7Cu2Fe, and Al2Mg3Zn3 were the preferred joint crack initiation locations, whereas Mg2Si was the major fracture initiation point of the parent material, and cracks tended to propagate along dense, coarse secondary phases, becoming more pronounced for larger cracks. In addition, as the stress ratio increased, non-Mg2Si phase fracture initiation points appeared in the BM. Meanwhile, the quantity of non-Mg2Si phases in the joints continued to increase, and the crack initiation sites became increasingly concentrated in the TMAZ-HAZ region.

Effect of Post-Weld Heat Treatment on Microstructure and Fracture Toughness of X80 Pipeline Steel Welded Joint.

In the current study, post-weld heat treatment (PWHT 580 °C) was used for an X80 pipeline steel-welded joint, and the fracture toughness of the welded joint was investigated using a crack tip opening displacement (CTOD) test. The relationship between microstructure evolution and fracture toughness is also discussed in this study. The results showed that the weld center mainly consisted of acicular ferrite (AF). The subcritical heat-affected zone (SCHAZ) consisted of a large amount of fine polygonal ferrite and some AF, and it maintained the rolling state of the base metal. The microstructure of the coarse-grained heat-affected zone (CGHAZ) was composed of granular bainite (GB) and M/A constituents, the latter of which decreased after the PWHT. The CTOD values of the weld center were in the range of 0.18-0.27 mm, while those of the CGHAZ were in the range of 0.02-0.65 mm. A brittle fracture occurred in the CGHAZ for both the as-welded and PWHT samples; the CTOD values were 0.042 mm and 0.026 mm, respectively. The CTOD values of the SCHAZ's location were in the range of 0.8-0.9 mm. The PWHT did not deteriorate the microstructure of the CGHAZ and had little influence on the fracture toughness of the X80 pipeline steel-welded joint; it ensured the fracture toughness of the welded joints and reduced the welding residual stress.

Effect of H2S Corrosion on the Fracture Toughness of the X80 Pipeline Steel Welded Joint.

To analyze the causes and mechanisms affecting the fracture toughness of X80 pipeline steel welded joints against H2S, the fracture toughness of different zones of X80 pipeline steel welded joints in both air and saturated H2S solution was investigated. The fracture toughness of welded joints degraded significantly in the saturated H2S solution, where the crack tip opening displacement (CTOD) characteristic value in the coarse grain heat-affected zone (CGHAZ) and weld metal (WM) was only 8% and 12% of that in air, respectively. However, the sub-critical grain heat-affected zone (SCHAZ) showed better resistance to H2S corrosion, with the CTOD characteristic value reaching 42% of that in air. The resistance of the welded joint to H2S corrosion was sensitive to microstructures. The grain boundary ferrite (GBF) presented in WM, and the angle of grain boundary orientation in CGHAZ was not conducive to hindering crack propagation. Moreover, the formation of the resultant hydrogen cracks owing to the H2S corrosion also reduced the fracture toughness of the welded joint.

Clinical practice of procalcitonin and hypersensitive c-reactive protein test in neonatal infection.

To study the clinical practice of procalcitonin and hypersensitive c-reactive protein test in neonatal infection. Two hundred cases of our hospital treatment confirmed infection early newborn children were selected from February 2014 to March 2015. According to the condition, the children were divided into four groups as follows: severe infection group, local infection group, non-infection group and healthy newborns group. At the same time, the new healthy newborns were chosen as control group. The levels of serum procalcitonin and high-sensitivity C-reactive protein were detected in all children and the levels in severe infection group children before and after treatment were also quantitatively detected and the test results were analyzed. There was significant difference in procalcitonin among the four groups (pS<0.05). The positive rate of the high-sensitivity C-reactive protein in local infection group has no significant difference compared with the non-infection group (p>0.05). But there was significant difference between the local infection group and healthy newborn group. As for the severe infection group, both the levels of procalcitonin and positive rate of high-sensitivity C-reactive protein had significant difference compared with the other groups. The detection of procalcitonin and high-sensitivity C-reactive protein could contribute to the diagnose of the early infection neonatal children and has important values in diagnosis and treatment of infectious diseases in the newborns.

The incidence of infants with rotavirus enteritis combined with lactose intolerance.

UNLABELLED: This study was to research the incidence of infants with rotavirus enteritis combined with lactose intolerance and the clinical effect of low lactose milk powder for infantile rotavirus enteritis with lactose intolerance. The control groups were 126 cases of infants with diarrhea randomly collected from our hospital at the same period, which their rotavirus detection was negative. The observation group was 185 cases of infants with rotavirus, which was tested to be positive. Through the urine galactose determination, 62 cases of the control group were positive and 124 cases of the observation group were positive. Then 124 cases of infants with rotavirus combined with lactose intolerance were randomly divided into two groups. 60 cases in the control group were given rehydration, correction of acidosis, oral smecta, Intestinal probiotics and other conventional treatment, then continued to the original feeding method. While, 64 cases in the treatment group, on the basis of routine treatment, applied the low lactose milk feeding. To observe the total effective rate for the two groups. The incidence of lactose intolerance in children with rotavirus enteritis (67.03%) was significantly higher than that of children with diarrhea (49.2%), which was tested to be negative. And the difference was statistically significant (p<0.5). In the aspect of reducing the frequency of diarrhea, and diarrhea stool forming time, the treatment group has the obvious superiority. The total effective rate was 95.4% for treatment group, which was higher than that in the control group (76.7%), the difference was statistically significant (P<0.05). CONCLUSION: Infants with rotavirus enteritis was easier to merge with lactose intolerance. The low lactose milk powder could improve the therapeutic effectively and could reduce the duration of disease, and restored to normal diet for 2 weeks feeding time.

Report: Prevention infection of newborn nosocomial and distribution of multiple drug resistant organism of the medicinal.

2124 neonates were monitored from February 2013 to August 2014, among which 1119 were admitted from outpatient department (outpatient group), 782 were transferred from other departments (other department group), and 223 were from other hospitals (other hospital group). Through it we explore the distribution of multidrug resistant organism in neonates, which were admitted to the hospital through various ways, and therefore analyze the risk factors of nosocomial infection to avoid cross infection of multi drug resistant organism in neonatology department. The results showed that 105 strains of multi drug resistant bacteria were detected in the neonatal department. Among them, there were 57 strains from the outpatient group, 27 from the other department group, and 21 from the other hospital group. Neonates with the hospitalization time of more than 14 days and low birth weight infants (1500 g) were the high-risk groups of drug-resistant strains in nosocomial infection. So the infection in neonates from other departments or hospitals should be strengthen, especially the prevention and control in neonates with the hospitalization time than 14 days and low birth weight infants (1500 g) in order to reduce the occurrence of multiple drug-resistant strains cross infection.

[Expression of cyclin A in childhood acute leukemia and its significance].

OBJECTIVE: To investigate the expression of cyclin A protein in childhood acute leukemia (AL) and its significance. METHODS: By using Western blotting analysis, cyclin A protein in bone marrow mononuclear cells from 47 newly diagnosed AL children and 33 non-hematological malignancy children was detected. RESULTS: The expression of cyclin A in AL group (0.38 +/- 0.20) was higher than that in control group (0.03 +/- 0.15) (P < 0.01). The expression of cyclin A in high risk acute lymphocyte leukemia (ALL) group (HR-ALL) (0.62 +/- 0.38) was higher than that in standard risk ALL group (SR-ALL) (0.33 +/- 0.33) (P < 0.05). The expression of cyclin A in WBC > or = 50 x 10(9)/L group and in WBC < 50 x 10(9)/L group was (0.64 +/- 0.36) and (0.39 +/- 0.38), respectively (P < 0.05). Eight (44.4%) out of 18 patients with positive cyclin A expression achieved complete remission (CR). The CR rate was lower than that of patients with negative cyclin A expression (100%) (P < 0.01). CONCLUSIONS: The higher expression of cyclin A may predict a poor prognosis for childhood ALL.