Cracking mechanism in as-cast GH4151 superalloy ingot with high γ'phase content

The fundamental mechanism of the cracking formation was investigated for the as-cast GH4151 superalloy.By analyzing the characteristics of cracking,the cracking mechanism was determined to be the cold crack formed during the cooling process.And cold cracking is closely related to severe segregation,complex precipitates and uneven γ'phase distribution.During cooling process,cracks were generated around the precipitates due to their different linear shrinkage coefficients.The annealing treatment process controlling the residual stress,the size and morphology of γ'phase was proposed.The annealing treatment plays a role in reducing residual stress through decreasing the thermal gradient and controlling the size distribution of γ'phase to reduce the strain concentration around the precipitate phases.

Incipient melting phase and its dissolution kinetics for a new superalloy

Based on XRD,SEM and EDS analyses,the phases in GH4151 alloy were identified.Differential scanning calorimetry(DSC)experiment and metallographic method were carried out to determine the incipient melting temperature(IMT)of the alloy.The result shows that the IMT of alloy is situated between 1150 and 1160℃.Subsequently,the dissolution process of Laves phase was carried out,and the dissolution kinetic equations were obtained at different temperatures.And then based on the verification of experiments,the model was confirmed to be credible to predict the fraction of the Laves phase dissolution.Finally,the results of diffusion coefficients indicate that the diffusion of Nb element is a critical factor for homogenization process of GH4151 alloy.

Spatial-temporal analysis of pulmonary tuberculosis in the northeast of the Yunnan province,People’s Republic of China

Background:The number of pulmonary tuberculosis(PTB)cases in China ranks third in the world.A continuous increase in cases has recently been recorded in Zhaotong prefecture-level city,which is located in the northeastern part of Yunnan province.This study explored the space-time dynamics of PTB cases in Zhaotong to provide useful information that will help guide policymakers to formulate effective regional prevention and control strategies.Methods:The data on PTB cases were extracted from the nationwide tuberculosis online registration system.Time series and spatial cluster analyses were applied to detect PTB temporal trends and spatial patterns at the town level between 2011 and 2015 in Zhaotong.Three indicators of PTB treatment registration history were used:initial treatment registration rate,re-treatment registration rate,and total PTB registration rate.Results:Seasonal trends were detected with an apparent symptom onset peak during the winter season and a registration peak during the spring season.A most likely cluster and six secondary clusters were identified for the total PTB registration rate,one most likely cluster and five secondary clusters for the initial treatment registration rate,and one most likely cluster for the re-treatment registration rate.The most likely cluster of the three indicators had a similar spatial distribution and size in Zhenxiong County,which is characterised by a poor socio-economic level and the largest population in Yunnan.Conclusion:This study identified temporal and spatial distribution of PTB in a high PTB burden area using existing health data.The results of the study provide useful information on the prevailing epidemiological situation of PTB in Zhaotong and could be used to develop strategies for more effective PTB control at the town level.The cluster that overlapped the three PTB indicators falls within the geographic areas where PTB control efforts should be prioritised.

Profiling B and T cell immune responses to co-infection of Mycobacterium tuberculosis and hookworm in humans

Background:Humoral and cellular immune responses play protective roles against Mycobacterium tuberculosis(MTB)infection.However,hookworm infection decreases the immune response to hookworm and bystander antigens.Currently,immune responses to co-infection of MTB and hookworm are still unknown,although co-infection has been one of the public health problems in co-endemic areas of pulmonary tuberculosis(PTB)and hookworm disease.Therefore,it is essential to evaluate B and T cell immune responses to the co-infection.Methods:Seventeen PTB cases co-infected with hookworm,26 PTB cases,15 patients with hookworm infection,and 24 healthy controls without PTB or hookworm infection were enrolled in the study.Expressions of CD3,CD4,CD8,CD10,CD19,CD20,CD21,CD25,CD27,CD38,FoxP3,and PD-1 were assessed on B and T cell subsets using multicolor flow cytometry.Results:For the B cell(CD19+)subsets,naïve B cells(CD10−CD27−CD21+CD20+),plasma cells(CD10−CD27+CD21−CD20−),and tissue-like memory B cells(CD10−CD27−CD21−CD20+)had higher proportions,whilst resting memory B cells(CD10−CD27+CD21+CD20+)had lower proportions in the group co-infected with MTB and hookworm as compared to other groups.Frequencies of activated memory B cells(CD10−CD27+CD21−CD20+)did not differ among the four groups.For the T cell(CD3+)subsets,frequencies of regulatory T cells(CD4+CD25+Foxp3+)and exhausted CD4+and CD8+T cells(CD4+PD-1+and CD8+PD-1+)were higher,and frequencies of activated CD4+and CD8+T cells(CD4+CD38+and CD8+CD38+)were lower in the co-infected group as compared to the other groups.Conclusion:The change patterns of the cell profile of circulating lymphocytes were indentified in human co-infection of MTB and hookworm,which might indicate that the humoral and cellular immune responses are more suppressed.

Space-time clustering and associated risk factors of pulmonary tuberculosis in southwest China

Background:Pulmonary tuberculosis(PTB,both smear positive and smear negative)is an airborne infectious disease of major public health concern in China and other parts of the world where PTB endemicity is reported.This study aims at identifying PTB spatio-temporal clusters and associated risk factors in Zhaotong prefecture-level city,located in southwest China,where the PTB notification rate was higher than the average rate in the entire country.Methods:Space-time scan statistics were carried out using PTB registered data in the nationwide TB online registration system from 2011 to 2015,to identify spatial clusters.PTB patients diagnosed between October 2015 and February 2016 were selected and a structured questionnaire was administered to collect a set of variables that includes socio-economic status,behavioural characteristics,local environmental and biological characteristics.Based on the discovery of detailed town-level spatio-temporal PTB clusters,we divided selected subjects into two groups including the cases that resides within and outside identified clusters.Then,logistic regression analysis was applied comparing the results of variables between the two groups.Results:A total of 1508 subjects consented and participated in the survey.Clusters for PTB cases were identified in 38 towns distributed over south-western Zhaotong.Logistic regression analysis showed that history of chronic bronchitis(OR=3.683,95%CI:2.180-6.223),living in an urban area(OR=5.876,95%CI:2.381-14.502)and using coal as the main fuel(OR=9.356,95%CI:5.620-15.576)were independently associated with clustering.While,not smoking(OR=0.340,95%CI:0.137-0.843)is the protection factor of spatial clustering.Conclusions:We found PTB specially clustered in south-western Zhaotong.The strong associated factors influencing the PTB spatial cluster including:the history of chronic bronchitis,living in the urban area,smoking and the use of coal as the main fuel for cooking and heating.Therefore,efforts should be made to curtail these associated factors.

Factors associated with primary transmission of multidrug-resistant tuberculosis compared with healthy controls in Henan Province, China

Background:It is estimated that there are about 74,000 primary multidrug-resistant tuberculosis(MDR-TB)patients per year according to the prevalence of MDR-TB of 5.7%among new TB patients in China.Thus,the risks of primary transmission of MDR-TB require further attention.This study aimed to identify the factors associated with primary transmission of MDR-TB in Henan province,where the number of new TB patients is ranked second highest in China.Methods:A 1:1 matched case–control study was conducted in Henan,China.Cases were primary MDR-TB patients who were individually matched with a healthy control without TB from the same neighborhood.The study was conducted from July 2013 to June 2014.Both case and control were matched by age(±5 years)and sex.Conditional logistic regression was used to compute adjusted odds ratios(AORs)with corresponding 95%confidence intervals(CIs)for risk factors associated with primary MDR-TB.Results:For the study,146 pairs of participants were recruited.The final multivariable logistic regression model disclosed that after adjusting for age and sex,primary MDR-TB cases were more likely to be single(AOR,5.4;95%CI,1.4–20.7),earn an annual income of≤12,000 yuan(RMB)(AOR,9.9;95%CI,2.0–48.1),experience more life pressure/stress(AOR,10.8;95%CI,2.8–41.5),not be medically insured(AOR,50.1;95%CI,8.2–306.8),and suffer from diabetes,cardiovascular disease or other respiratory diseases,or cancer(AOR,57.1;95%CI,8.6–424.2).Conclusions:In order to control primary transmission of MDR-TB in China,we recommend that improving the social support,living standards and medical security of the lower social class become a priority.

Analysis and predication of tuberculosis registration rates in Henan Province, China: an exponential smoothing model study

Background The World Health Organization End TB Strategy meant that compared with 2015 baseline,the reduction in pulmonary tuberculosis(PTB)incidence should be 20 and 50%in 2020 and 2025,respectively.The case number of PTB in China accounted for 9%of the global total in 2018,which ranked the second high in the world.From 2007 to 2019,854672 active PTB cases were registered and treated in Henan Province,China.This study was to assess whether the WHO milestones could be achieved in Henan Province.Methods The active PTB numbers in Henan Province from 2007 to 2019,registered in Chinese Tuberculosis Information Management System were analyzed to predict the active PTB registration rates in 2020 and 2025,which is conductive to early response measures to ensure the achievement of the WHO milestones.The time series model was created by monthly active PTB registration rates from 2007 to 2016,and the optimal model was verified by data from 2017 to 2019.The Ljung-Box Q statistic was used to evaluate the model.The statistically significant level isα=0.05.Monthly active PTB registration rates and 95%confidence interval(CI)from 2020 to 2025 were predicted.Results High active PTB registration rates in March,April,May and June showed the seasonal variations.The exponential smoothing winter’s multiplication model was selected as the best-fitting model.The predicted values were approximately consistent with the observed ones from 2017 to 2019.The annual active PTB registration rates were predicted as 49.1(95%CI:36.2–62.0)per 100000 population and 34.4(95%CI:18.6–50.2)per 100000 population in 2020 and 2025,respectively.Compared with the active PTB registration rate in 2015,the reduction will reach 23.7%(95%CI,3.2–44.1%)and 46.8%(95%CI,21.4–72.1%)in 2020 and 2025,respectively.Conclusions The high active PTB registration rates in spring and early summer indicate that high risk of tuberculosis infection in late autumn and winter in Henan Province.Without regard to the CI,the first milestone of WHO End TB Strategy in 2020 will be achieved.However,the second milestone in 2025 will not be easily achieved unless there are early response measures in Henan Province,China.

Rapid assessment of knowledge,attitudes,practices,and risk perception related to the prevention and control of Ebola virus disease in three communities of Sierra Leone

Background:The recent outbreak of the Ebola virus disease(EVD)in Sierra Leone has been characterized by the World Health Organization as one of the most challenging EVD outbreaks to date.The first confirmed case in Sierra Leone was a young woman who was admitted to a government hospital in Kenema following a miscarriage on 24 May 2014.On 5 January 2015,intensified training for an EVD response project was initiated at the medical university of Sierra Leone in Jui.To understand the knowledge,attitudes,practices,and perceived risk of EVD among the public,especially after this training,a rapid assessment was conducted from 10 to 16 March 2015.Methods:Interviews were conducted with 466 participants based on questionnaires that were distributed from 10 to 16 March 2015 by cluster sampling in three adjacent communities,namely Jui,Grafton,and Kossoh Town,in the Western Area Rural District of Sierra Leone.Results:It was found that knowledge about EVD was comprehensive and high.Positive attitude towards prevention was found to be satisfactory.Nearly all participants knew the reporting phone number 117 and had reported some change in behavior since learning about Ebola.More than half(62%)of the participants had a history of travelling to urban areas,which increases the risk of infection.The multivariable logistic regression analysis showed that community and occupation were variables associated with perceived risk of EVD.Conclusions:Our study showed that community level social mobilization and community engagement were an effective strategy in the special context.

A practical community-based response strategy to interrupt Ebola transmission in sierra Leone, 2014–2015

Background:The Ebola virus disease spread rapidly in West Africa in 2014,leading to the loss of thousands of lives.Community engagement was one of the key strategies to interrupt Ebola transmission,and practical community level measures needed to be explored in the field and tailored to the specific context of communities.Methods:First,community-level education on Ebola virus disease(EVD)prevention was launched for the community’s social mobilizers in six districts in Sierra Leone beginning in November 2014.Then,from January to May of 2015,in three pilot communities,local trained community members were organized to engage in implementation of EVD prevention and transmission interruption measures,by involving them in alert case report,contact tracing,and social mobilization.The epidemiological indicators of transmission interruption in three study communities were evaluated.Results:A total of 6016 community social mobilizers from 185 wards were trained by holding 279 workshops in the six districts,and EVD message reached an estimated 631680 residents.In three pilot communities,72 EVD alert cases were reported,with 70.8%of them detected by trained local community members,and 14 EVD cases were finally identified.Contact tracing detected 64.3%of EVD cases.The median duration of community infectivity for the cases was 1 day.The secondary attack rate was 4.2%,and no third generation of infection was triggered.No health worker was infected,and no unsafe burial and noncompliance to EVD control measures were recorded.The community-based measures were modeled to reduce 77 EVD cases,and the EVD-free goal was achieved four months earlier in study communities than whole country of Sierra Leone.Conclusions: The community-based strategy of social mobilization and community engagement was effective in casedetection and reducing the extent of Ebola transmission in a country with weak health system. The successfullypractical experience to reduce the risk of Ebola transmission in the community with poor resources would potentiallybe helpful for the global community to fight against the EVD and the other diseases in the future.