In situ analysis of deformation twins within a magnesium polycrystal: (II) twin growth.

The process of twin growth is difficult to be captured instantaneously. Synchrotron polychromatic X-ray microdiffraction (micro-XRD) is applied to in situ study twin growth in extruded Mg-3Al-1Zn polycrystal subjected to uniaxial tension. The micro-XRD data is used to map an area of 396 × 200 µm2 under the loading levels from 12 MPa to 73 MPa. The orientations of seven parents and ten resultant twins are determined by indexing Laue patterns, while their morphologies are mapped by the integrated intensities of particular reflections. {101¯2} twins are detected at 64 MPa. The maximum SF criterion for twin variant selection is invalid here. Twin growth rates are deduced from the variation of integrated intensities between 64 MPa and 68 MPa. It is found that twin growth rates in the HCP material are not proportional to active twin's SF values, though the SF value is related to the magnitude of driving resource. Twin growth rate exhibits obvious anisotropy, either for lengthwise growth rate or thickness growth rate. When two twins within a parent belong to the same twin variant, they exhibit similar growth rates. Meanwhile, when two twins within a parent come across, one can block the other and the latter occur shrinking.

Drug Resistance of Pathogens Causing Nosocomial Pulmonary Infection in Stroke Patients / 中华医院感染学杂志

OBJECTIVE To investigate drug resistance status of the pathogens of nosocomial pulmonary infection in stroke patients and to provide the scientific reference for clinical prevention of nosocomial infections and reasonable use of antibiotics.METHODS By the methods combining prospective monitoring and retrospective review,patients′ clinical data were analyzed statistically.Referring to National Rules of Procedures in Clincal Laboratory,the strains were identified.The antibiotic susceptibility test was performed by K-B method and the results were read according to CLSI 2006.RESULTS The main pathogens of nosocomial pulmonary infection in stroke patients were Klebsiella Pneumoniae(22.0%),Pseudomonas aeruginosa(18.4%),Acinetobacter baumannii(12.7%),Staphylococcus aureus(12.3%) and Escherichia coli(11.4%).The detection rate of extensive-spectrum beta-lactamase(ESBLs) producing E.coli and K.pneumoniae was 43.2%.Meticillin-resistant S.aureus(MRSA) accounted for 39.0%.Pan-drug resistant strains were found in A.baumannii.CONCLUSIONS Drug resistance status of pathogens of nosocomial pulmonary infection in stroke patients is very serious.We should take intervention measures to prevent and control the onest and prevalence of resistant strains.

Pathogenic Distribution and Intervention Strategy of Nosocomial Infection in Tumor Department / 中华医院感染学杂志

OBJECTIVE To approach the pathogenic distribution of nosocomial infection and drug-resistance in tumor department to formulate the intervention strategy.METHODS Prospective monitoring and retrospective investigation were performed to analyze the 198 cases of nosocomial infection in tumor department.RESULTS The lower respiratory tract infection was the main infection in tumor department,accounted for 68.2%.The urinary tract infection rated the second,accounted for 16.7%.Pathogenic bacteria mainly included Pseudomonas aeruginosa(20.2%),Klebsiella pneumoniae(19.2%),Escherichia coli(16.2%),Staphylococcus aureus(10.6%),etc.Above pathogenic bacteria were all multidrug-resistant.Detection rate of extended spectrum ?-lactamases(ESBLs) producing Enterobacteriaceae strains was 45.7%.Detection rate of meticillin-resistant staphylococci(MRS) was 40.6%.CONCLUSIONS The drug-resistance status of nosocomial infection is very serious in tumor department.Comprehensive intervention strategy should be adopted to decrease the infection rate.

Detection of Double Mutation of Basal Core Promoter(BCP) of HBV by TaqMan MGB / 中华医院感染学杂志

OBJECTIVE To establish a simple,sensitive method for detecting the double mutation of the basal core promoter(BCP) of HBV.METHODS FAM fluorescence-labeled TaqMan MGB and primers driving from the region containing the double mutation of BCP were designed for the real time PCR,then the standard positive control,standard negative control and HBV DNA were amplified and detected by the real time PCR.The results of detecting the double mutation of BCP were validated by the direct-sequencing analysis of PCR products.RESULTS The double mutation of BCP of HBV could be detected by the real time PCR.The sensitivity of the method was 3?100 copy templates and as few as 1% of mutant among wild-type virus sequence were detected.CONCLUSIONS The method can be used to detect the double mutation of BCP of serum HBV DNA.