[Population's acceptance and attitude toward a novel fecal immunochemical test for colorectal cancer screening: a multi-center survey in China]

Objective: To investigate the acceptance and attitude toward a novel fecal immunochemical test (FIT) in colorectal cancer screening among populations in China. Methods: From May 2018 to May 2019, 2 474 people aged 50-74 years were recruited from five provinces of China (Zhejiang, Anhui, Jiangsu, Hunan and Yunnan). The general demographic characteristics, acceptance of the new FIT technology and operational difficulties through the whole screening process were obtained through questionnaire survey. Multivariate logistic regression model was used to analyze the factors related to difficulties encountered in sampling stool, reading and uploading results. Results: The subjects were (60.0±6.4) years old, and female, high school of above educated, unemployed/retired/other, married and with medical insurance status of "new rural cooperative medical care (NRCMC)" accounted for 61.7% (1 526), 29.0%(718), 34.3% (849), 92.7% (2 293) and 31.3%(775), respectively. The population's acceptance of the FIT technology was 94.8%. In the process of FIT screening, the percentage of occurred difficulties in sampling stool, reading and uploading results were 33.1% (819), 46.4% (1 147) and 62.9% (1 557), respectively. The main difficulties were the uncertainty about whether the sampling operation was standard (28.0%), the inability to accurately judge the result displayed (32.5%) and the need for help without using a smartphone (44.2%). The results of multivariate logistic regression model analysis showed that people aged 65-74 years old and with medical insurance status of "NRCMC" were more likely to encounter difficulties in sampling, and those who were unemployed/retired/other and living with 3 or more family members were less likely to encounter difficulties in sampling. Those aged 65-74 years old, farmers or migrant workers, and those with "NRCMC" were more likely to encounter difficulties in readingresults, and those with 3 or more family members were less likely to encounter difficulties in reading result. Those with "NRCMC" were more likely to encounter difficulties in uploading results, and those with education level of high school or above, living with more than 3 family members were less likely to encounter difficulties in uploading results. Conclusion: The acceptance of the new FIT technology is relatively high among the subjects. Age, education level, occupation, number of family members living together and medical insurance status might be related to difficulties encountered in sampling stool, reading and uploading results, and it can be further strengthened in terms of the technology and characteristics of sub-populations.

[Analysis on the consciousness of the cancer early detection and its influencing factors among urban residents in China from 2015 to 2017]

Objective: To understand the consciousness of the cancer early detection among urban residents and identify the influencing factors from 2015 to 2017. Methods: A cross-sectional survey was conducted in 16 provinces covered by the Cancer Screening Program in Urban China from 2015 to 2017. A total of 32 257 local residents aged ≥18 years old who could understand the investigation procedure were included in the study by using the cluster sampling method and convenient sampling method. All local residents were categorized into four groups, which contained 15 524 community residents, 8 016 cancer risk assessment/screening population, 2 289 cancer patients and 6 428 occupational population, respectively. Self-designed questionnaires were used to collect population, socioeconomic indicators, self-cancer risk assessment, regular participation in physical examination and other information. The multivariate logistic regression model was used to identify the factors of people who had not regularly participated in the regular physical examination in the past five years. Results: The self-assessment results of 32 357 residents showed that there were 27.54% (8 882) of total study population with self-reported cancer risk, 45.48% (14 671) without cancer risk and 26.98% (8 704) with unclear judgement on their own cancer risk. Among population with cancer risk, 79.84% (7 091) considered physical examination accounted. In the past five years, there were 21 105 (65.43%) residents participated in regular physical examination and 11 148 (34.56%) participated in non-scheduled one, respectively. The multivariate logistic regression analysis showed that compared with unmarried and western region residents, divorced, middle and eastern region residents had a stronger consciousness to participate in the regular physical examination (P<0.05). Compare with residents with annual household income less than 20 000 CNY in 2014, cancer risk assessment/screening intervention population, and self-assessment with cancer risk, residents with annual household income between 20 000 CNY and 59 000 CNY in 2014, occupational population, community residents, cancer patients, self-reported cancer-free risk, and self-assessment with unclear judgement of cancer risk were less likely to participate in the regular physical examination (all P values <0.05). Conclusion: From 2015 to 2017, the Chinese urban residents had a acceptable consciousness of the cancer early detection. The marital status, annual household income, population group and self-assessment of cancer risk were related to the consciousness of the cancer early detection of people who had not participated in the regular physical examination in the past five years.

[Analysis on the demand, access and related factors of cancer prevention and treatment knowledge among urban residents in China from 2015 to 2017]

Objective: To investigate the demand and access to the cancer prevention and treatment knowledge and related factors among urban residents in China from 2015 to 2017. Methods: A cross-sectional survey was conducted in 16 provinces covered by the Cancer Screening Program in Urban China from 2015 to 2017. A total of 32 257 local residents aged ≥18 years old who could understand the investigation procedure were included in the study by using the cluster sampling method and convenient sampling method. All local residents were categorized into four groups, which contained 15 524 community residents, 8 016 cancer risk assessment/screening population, 2 289 cancer patients and 6 428 occupational population, respectively. The self-designed questionnaire was used to collect the information of general demographic characteristics, the demand and access to cancer prevention and treatment knowledge, and the influencing factors of the attitude. The Chi-square test was used to analyze the difference of the demand of the cancer prevention knowledge among different groups and the corresponding factors of the cancer prevention and treatment knowledge were analyzed by using the logistic regression model. Results: The proportion of residents who need the cancer prevention and treatment knowledge was 79.5%. The demand rate of the inducement, symptom and diagnosis methods of cancer in the occupational population was highest, about 66.8%, 71.0% and 20.8%, respectively. The demand rate of treatment methods and cost in current cancer patients was the highest, about the 45.9% and 21.9%, respectively. The top three sources to acquire the cancer prevention and treatment knowledge were "broadcast or television" (69.5%), "books, newspapers, posters or brochures" (44.7%) and "family and friends" (33.8%). The multivariate analysis showed that compared with public institution personnel/civil servants, unmarried/cohabiting/divorced/widowed and others, annual household income less than 20 000 CNY, from the eastern region, people without cancer diagnosis and people with self-assessment of cancer risk, the demand rate of cancer prevention and treatment knowledge was higher in enterprise personnel/workers, married, annual household income between 60 000 CNY and 150 000 CNY, from the central region, people with cancer and people with unclear cancer risk (all P values <0.05). Conclusion: There was a high demand for the cancer prevention and treatment knowledge among urban residents in China from 2015 to 2017. The main access to the knowledge is from the radio or television. The occupation, marital status, annual household income, residential region, health status and risk of disease were the main factors of the demand of the cancer prevention and treatment knowledge.

[Study on the health literacy and related factors of the cancer prevention consciousness among urban residents in China from 2015 to 2017]

Objective: To understand the health literacy and relevant factors of cancer prevention consciousness in Chinese urban residents from 2015 to 2017. Methods: A cross-sectional survey was conducted in 16 provinces covered by the Cancer Screening Program in Urban China from 2015 to 2017. A total of 32 257 local residents aged ≥18 years old who could understand the investigation procedure were included in the study by using the cluster sampling method and convenient sampling method. All local residents were categorized into four groups, which contained 15 524 community residents, 8 016 cancer risk assessment/screening population, 2 289 cancer patients and 6 428 occupational population, respectively. The self-designed questionnaire was used to collect the information of demographic characteristics and cancer prevention consciousness focusing on nine common risk factors, including smoking, alcohol, fiber food, food in hot temperature or pickled food, chewing betel nut, helicobacter pylori, moldy food, hepatitis B infection, estrogen, and exercise. The logistic regression model was adopted to identify the influencing factors. Results: The overall health literacy of the cancer prevention consciousness was 77.4% (24 980 participants), with 77.4% (12 018 participants), 79.9% (6 406 participants), 77.2% (1 766 participants) and 74.5% (4 709 participants) in each group (P<0.001). The correct response rates for nine risk factors ranged from 55.2% to 93.0%. The multivariate logistic regression analysis showed that compared with community residents, people with primary school level education or below, and the number of people living together in the family <3, the cancer risk assessment/screening intervention population, cancer patients, those with junior high school level educationor above and the number of people living in the family ≥3 had better health literacy of the cancer prevention consciousness (all P values <0.05). Compared with females, 39 years old and below, government-affiliated institutions or civil servants, from the eastern region, males, older than 40 years, company or enterprise employees, and from the middle or western region had worse health literacy of the cancer prevention consciousness (all P values <0.05). Conclusion: The health literacy of the cancer prevention consciousness in Chinese urban residents should be improved. The cancer screening intervention, gender, age, education, occupation, the number of people co-living in the family, and residential region were associated with the health literacy of the cancer prevention consciousness.

[Analysis on the health literacy of the cancer prevention and treatment and its related factors among urban residents in China from 2015 to 2017]

Objective: To understand the health literacy of the cancer prevention and treatment among urban residents of China, and explore the related factors. Methods: A cross-sectional survey was conducted in 16 provinces covered by the Cancer Screening Program in Urban China (CanSPUC) from 2015 to 2017. A total of 32 257 local residents aged ≥18 years old who could understand the investigation procedure were included in the study by using the cluster sampling method and convenient sampling method. All local residents were categorized into four groups, which contained 15 524 community residents, 8 016 cancer risk assessment/screening population, 2 289 cancer patients and 6 428 occupational population, respectively. The health literacy of the cancer prevention, early discovery, early diagnosis, early treatment and the demands of cancer prevention and treatment knowledge was analyzed. The level of health literacy among different groups were calculated and compared. The binary logistic regression model was used to analyze the influencing factors of the health literacy of the cancer prevention and treatment. Results: The level of health literacy of the cancer prevention and treatment was 56.97% among all study population; in each group it was 55.01% for community residents, 59.08% for cancer risk assessment/screening population, 61.99% for cancer patients and 57.31% for occupational population, respectively (P<0.001). The level of health literacy of the cancer prevention and treatment of residents aged 50 to 69 years old, other occupational groups, unmarried, the central and western region residents and the group with unclear self-assessment of cancer risk was significantly lower than that of residents younger than 40 years old, personnel of public institutions/civil servants, married, the eastern region residents and the group whose self-assessment without cancer risk (P<0.05) . The level of health literacy of cancer prevention and treatment of females, people who went to high school or over, cancer risk assessment/screening population, cancer patients and occupational population was significantly higher than that of males, people who had an education level of primary school or below and community residents (P<0.05) . Conclusion: The health literacy of the cancer prevention and treatment of urban residents in China was relatively high, but there was still room for improvement. Gender, age, educational level, occupation, region, marital status, self-assessment of cancer risk, and type of respondents were the key influencing factors of the health literacy of the cancer prevention and treatment. Male, 50-69 years old, lower educational level, central and western regions, unclear cancer risk self-assessment, and without specific environmental exposure to cancer prevention and treatment knowledge or related risk factors were the characteristics of the key intervention group of the health literacy of the cancer prevention and treatment.

[Analysis on the consciousness of the early cancer treatment and its influencing factors among urban residents in China from 2015 to 2017]

Objective: To understand the consciousness of the cancer early treatment and its demographic and socioeconomic factors. Methods: A cross-sectional survey was conducted in 16 provinces covered by the Cancer Screening Program in Urban China (CanSPUC) from 2015 to 2017. A total of 32 257 local residents aged ≥18 years old who could understand the investigation procedure were included in the study by using the cluster sampling method and convenient sampling method. All local residents were categorized into four groups, which contained 15 524 community residents, 8 016 cancer risk assessment/screening population, 2 289 cancer patients and 6 428 occupational population, respectively. The questionnaire collected personal information, the consciousness of the cancer early treatment and relevant factors. The Chi square test was used to compare the difference between the consciousness of the cancer early treatment and relevant factors among the four groups. The logistic regression model was used to analyze the influencing factors related to the consciousness of the cancer early treatment. Results: With the assumption of being diagnosed as precancer or cancer, 89.97% of community residents, 91.84% of cancer risk assessment/screening population, 93.00% of cancer patients and 91.52% of occupational population would accept active treatments (P<0.001). If the immediate family members were diagnosed as precancer or cancer, people who would encourage their family members to receive early treatment in the four groups accounted for 91.96%, 91.94%, 92.44% and 91.55%, respectively (P<0.001). The company employees, annual household income with 40 000 yuan and more and other three groups had a relatively better consciousness of the cancer early treatment (P<0.05). Male, widowed, unemployed and from the central and western regions had a relatively worse consciousness of the cancer early treatment (P<0.05). Conclusion: Residents in urban China participants had a good consciousness of the cancer early treatment. The marital status, occupation, annual household income and residential regions were major factors related to the consciousness of the cancer early treatment.

[Natural history of colorectal cancer: a Meta-analysis on global prospective cohort studies]

Objective: To acknowledge the availability and rates of annual transition of outcomes during the progression and regression stages of colorectal cancer (CRC) and related diseases, by pooling global follow-up studies on the natural history of CRC. Methods: Till March, 2017, data was collected through systematic literature review over multiple databases, including PubMed, Embase, Cochrane and Chinese Biology Medicine (CBM) disc. Information regarding the characteristics, classification system of health states, related outcomes and incidence rates on CRC or high-risk adenoma for the surveillance cohorts of the studies, were extracted and summarized. Both Meta and sensitivity analyses were performed on those outcomes if they appeared in more than 3 studies, using the random effects model. Annual transition rate with 95%CI was used to estimate each of the outcomes, Quality of the studies was assessed, using the Newcastle-Ottawa Scale. Results: A total of 29 cohort studies were included, with the mean follow-up period as 5.7 years. All studies except one, focused on adenoma-carcinoma pathway and reported the outcome parameters of adenomas by different risk, and some reported the findings on different sizes (n=6) of adenomas. These cohorts were divided into three groups (normal status, with low-risk or high-risk adenoma) according to the status of baseline endoscopic pathologic findings. Their available outcome parameters, corresponding number of involved articles, aggregated sample size and pooled annual transition rates were presented. Six parameters were obtained in the normal cohorts, including those from normal to low-risk adenoma (16 articles, 58 235, 0.030: 0.024-0.037), to high-risk adenoma (17 articles, 62 089, 0.003: 0.002-0.004), to diminutive adenoma (<5 mm, 4 articles, 1 277, 0.021: 0.013-0.029), to small adenoma (6-9 mm, 4 articles, 1 277, 0.006: 0.001-0.010), to large adenoma (≥10 mm, 7 articles, 3 531, 0.002: 0.000-0.003) and to CRC (19 articles, 104 836, 0.000 3: 0.000 2-0.000 5). Three parameters were obtained in low-risk adenoma in cohorts with polypectomy findings, including recurrence (9 articles, 4 788, 0.109: 0.062-0.157) from low-risk adenoma after polypectomy to high-risk adenoma (10 articles, 5 736, 0.009: 0.004-0.013) and to CRC (12 articles, 11 347, 0.000 6: 0.000 4-0.000 8). Three parameters were obtained on high-risk adenoma from cohorts with polypectomy findings, including recurrence (12 articles, 7 030, 0.038: 0.028-0.048) from high-risk adenoma after polypectomy to low-risk adenoma (8 articles, 2 489, 0.133: 0.081-0.185) and CRC (14 articles, 14 899, 0.002: 0.001-0.003). Except for normal to low-risk adenomas, results from the sensitivity analysis for the other parameters showed stable. Of the included studies, two presented incidence rates of CRC in different clinical stages and the another two were focusing on the parameters related to serrated pathway. Conclusions: Globally, follow-up studies reported data on natural history of colorectal cancer is of paucity. Compared to the "adenoma-carcinoma" pathway, transition parameters of the serrated lesion pathway are more limited. This Meta-analysis provided convincing evidence for optimizing the strategies regarding follow-up program on the disease, using the baseline endoscopic findings from global CRC Screening Program. These results also offered strong data-related support for Chinese population- specific interventional model on colorectal cancer.

[Constituent and workload of service providers engaged in cancer screening: findings and suggestions from a multi-center survey in China]

Objective: To understand the constituent and workload of service providers engaged in cancer screening in China and provide evidence for the assessment of the sustainability of national cancer screening project. Methods: Using either questionnaire or online approach, the survey was conducted in 16 provinces, where Cancer Screening Program in Urban China (CanSPUC) was conducted, from 2014 to 2015. The medical institutes surveyed included hospitals [71.1% were class Ⅲ(A) hospitals], centers for disease control and prevention (CDCs) and community centers where cancer screening was undertaken during 2013-2015. The questionnaire survey was conducted among the staffs responsible for the overall coordination, management and implementation of the screening project to collect the information about the allocation, workload and compensation of the service providers from different specialties. Results: A total of 4 626 staffs were surveyed in this study, their average age was (37.7±9.5) years, and males accounted for 31.0%. Human resources allocated differed with province. The number of senior staff ranged from 6 (Chongqing) to 43 (Beijing) among the 8 comparable provinces. Among the staffs surveyed, 2 192 were from hospitals, 431 were from CDCs and 1 990 were from community centers, and the staffs who complained heavy workload accounted for 19.9%, 24.6% and 34.1% respectively (P<0.001). Among 227 staffs for overall coordination, 376 management staffs and 3 908 staffs for implementation, those who complained heavy workload accounted for 23.6%, 22.3% and 28.2% respectively (P<0.001). A total of 3 244 staffs (73.8%) got compensations for heavy workload. The compensation types were manly labor fee linked with workload (67.5%) and labor fee regardless workload (26.6%). Conclusion: The province specific differences in human resources allocation indicated the differences in screening project's organizing pattern and capability. It is suggested to conduct routine cancer screening (using specialized staffs), reduce the workload of the first line and community staffs and increase the compensation for the service providers for the sustainability of cancer screening project in China.

[Willingness of potential service suppliers to provide cancer screening in urban China]

Objective: Based on the investment for potential suppliers of cancer screening services, we assessed the reasons that affecting their participation motivation related to the long-term sustainability of cancer screening in China. Methods: Hospitals that had never been involved in any national level cancer screening project were selected by using the convenient sampling method within the 16 project cities of Cancer Screening Program in Urban China (CanSPUC) with 1 or 2 hospitals for each city. All the managers from the institutional/department level and professional staff working and providing screening services in these hospitals, were interviewed by paper-based questionnaire. SAS 9.4 was used for logical verification and data analysis. Results: A total of 31 hospitals (18 hospitals at the third level and, 13 hospitals at the second level) and 2 201 staff (508 hospital and clinic unit managers, 1 693 professional staff) completed the interview. All the hospitals guaranteed their potential capacity in service providing. 92.5% hospital managers showed strong willingness in providing cancer screening services, while 68.3% of them declared that the project fund-raising function was the responsibility of the government. For professional staff, their prospect gains from providing screening service would include development on professional skills (72.4%) and material rewards (46.8%). Their main worries would include extra work for CanSPUC might interfere their routine work (42.1%) plus inadequate compensation (41.8%). Medians of the prospect compensation for extra work ran between 20 to 90 Chinese Yuan per screening item respectively. For all the screening items, workers from the third-level hospitals expected their compensation to be twice as much of those working at the second level hospitals. Conclusion: Professional capacity building and feasible material incentive seemed to be the two key factors that influenced the sustainability and development of the programs.

[Potential demand on cancer screening service in urban populations in China: a cross-sectional survey]

Objective: To understand the acceptance and personal demand for cancer screening service among the urban residents who had never been involved in any national level cancer screening programs in China and identify the key factors influencing the sustainability of cancer screening. Methods: A questionnaire survey was conducted among the local people aged 40-69 years selected through convenience sampling in 16 provinces of China to collect the general information about their demands for the screening service and others. Results: A total of 16 394 qualified questionnaires were completed. The average age of the people surveyed was (53.8±8.0) years, and men accounted for 44.6%. Without concerning the cost, 4 831 people (29.5%) had no demands for cancer screening services, the reasons are as follow: they would like to go to see doctors only when they were ill (61.8%); they had already received similar medical examinations (36.8%) and they would like to receive cancer screening directly without pre-health risk assessment (33.0%). Among the people surveyed, 10 795 (65.8%) had demands for cancer screening services, but they had choice on the screening settings, 43.7% wanted to receive the service in a general hospitals, while 36.5% would like to go to cancer-specialized hospitals. As for the level of medical institutes providing cancer screening service, 61.4% of the people surveyed would choose a higher level one, while 36.4% would choose an ordinary one. On screening procedures, 61.5% of the people surveyed would accept the mode of "clinical examination after questionnaire-assessment" . Conclusion: Most people surveyed had demands for cancer screening services and they would like to receive the screening services in higher level medical institutes. It is suggested to spread cancer screening know ledge, and strengthen the capability building of screening in grass root medical institutes to attract more people to receive cancer screening.

[Preference on screening frequency and willingness-to-pay for multiple-cancer packaging screening programs in urban populations in China]

Objective: From an actual cancer screening service demanders' perspective, we tried to understand the preference on screening frequency and willingness-to-pay for the packaging screening program on common cancers and to evaluate its long-term sustainability in urban populations in China. Methods: From 2012 to 2014, a multi-center cross-sectional survey was conducted among the actual screening participants from 13 provinces covered by the Cancer Screening Program in Urban China (CanSPUC). By face-to-face interview, information regarding to preference to screening frequency, willingness-to-pay for packaging screening program, maximum amount on payment and related reasons for unwillingness were investigated. Results: A total of 31 029 participants were included in this survey, with an average age as (55.2±7.5) years and median annual income per family as 25 000 Chinese Yuan. People's preference to screening frequency varied under different assumptions ( " totally free" and "self-paid" ). When the packaging screening was assumed totally free, 93.9% of residents would prefer to take the screening program every 1 to 3 years. However, the corresponding proportion dropped to 67.3% when assuming a self-paid pattern. 76.7% of the participants had the willingness-to-pay for the packaging screening, but only 11.2% of them would like to pay more than 500 Chinese Yuan (the expenditure of the particular packaging screening were about 1 500 Chinese Yuan). The remaining 23.3% of residents showed no willingness-to-pay, and the main reasons were unaffordable expenditure (71.7%) and feeling'no need'(40.4%). Conclusions: People who participated in the CanSPUC program generally tended to choose high-frequency packaging screening program, indicating the high potential acceptance for scale-up packaging screening, while it needs cautious assessments and rational guidance to the public. Although about seven in ten of the residents were willing to pay, the payment amount was limited, revealing the necessity of strengthening individual's awareness of his or her key role in health self-management, and a reasonable payment proportion should be considered when establishing co-compensation mechanism.

[Willingness and preferences of actual service suppliers regarding cancer screening programs: a multi-center survey in urban China]

Objective: From the perspective of actual service suppliers regarding cancer screening, this study aimed to assess the long-term sustainability of cancer screening programs in China. Methods: Based on a Cancer Screening Program in Urban China (CanSPUC), our survey focused on all the hospitals, centers for disease control and prevention (CDC) and community service centers across 16 provinces in China which participated in the programs between 2013 and 2015. All the managers (institutional/department level) and professional staff involved in the program were interviewed using either paper-based questionnaire or online approach. Results: A total of 4 626 participants completed the interview. It showed that the main gains from providing screening service emphasized promotion in social value (63.6%), local reputation (35.9%), and professional skills (30.6%), whereas difficulties encountered included inadequate compensation (30.9%) and discordance among information systems (28.3%). When the service remuneration amounts to about 50 Chinese Yuan per screening item, those professional staff self-reported that they would like to work overtime. More than half (63.7%) of the staff expressed willingness to provide routine screening service, the main expectations were to promote their reputation to the local residents (48.7%) and to promote professional skills (43.1%). Those who were not willing to provide screening services were worried about the potential heavy workload (59.8%) or being interfered with their routine work (49.8%). Further detailed results regarding the different organization types and program roles were presented in the following detailed report. Conclusions: Findings of gains and difficulties showed that if cancer screening is expected to become a long-term running, incentive mechanism from the program, external promotion and advocacy as well as capacity building should be strengthened; furthermore, rewards to staff's screening services should be raised according to the local situations. Results regarding the "willingness to provide service" showed that management of the program should also be strengthened, including information system building and inter-agency and inter-department coordination at the government levels.

New atom probe approaches to studying segregation in nanocrystalline materials

Atom probe is a technique that is highly suited to the study of nanocrystalline materials. It can provide accurate atomic-scale information about the composition of grain boundaries in three dimensions. In this paper we have analysed the microstructure of a nanocrystalline super-duplex stainless steel prepared by high pressure torsion (HPT). Not all of the grain boundaries in this alloy display obvious segregation, making visualisation of the microstructure challenging. In addition, the grain boundaries present in the atom probe data acquired from this alloy have complex shapes that are curved at the scale of the dataset and the interfacial excess varies considerably over the boundaries, making the accurate characterisation of the distribution of solute challenging using existing analysis techniques. In this paper we present two new data treatment methods that allow the visualisation of boundaries with little or no segregation, the delineation of boundaries for further analysis and the quantitative analysis of Gibbsian interfacial excess at boundaries, including the capability of excess mapping.

New deformation twinning mechanism generates zero macroscopic strain in nanocrystalline metals

Macroscopic strain was hitherto considered a necessary corollary of deformation twinning in coarse-grained metals. Recently, twinning has been found to be a preeminent deformation mechanism in nanocrystalline face-centered-cubic (fcc) metals with medium-to-high stacking fault energies. Here we report a surprising discovery that the vast majority of deformation twins in nanocrystalline Al, Ni, and Cu, contrary to popular belief, yield zero net macroscopic strain. We propose a new twinning mechanism, random activation of partials, to explain this unusual phenomenon. The random activation of partials mechanism appears to be the most plausible mechanism and may be unique to nanocrystalline fcc metals with implications for their deformation behavior and mechanical properties.

Compact and dissociated dislocations in aluminum: implications for deformation

Atomistic simulations, confirmed by electron microscopy, show that dislocations in aluminum can have compact or dissociated cores. The calculated minimum stress (sigma(P)) required to move an edge dislocation is approximately 20 times smaller for dissociated than for equivalent compact dislocations. This contradicts the well accepted generalized stacking fault energy paradigm that predicts similar sigma(P) values for both configurations. Additionally, Frank's rule and the Schmid law are also violated because dislocation core energies become important. These results may help settle a 50-year-old puzzle regarding the magnitude of sigma(P) in face-centered-cubic metals, and provide new insights into the deformation of ultra-fine-grained metals.

Ultralong single-wall carbon nanotubes

Since the discovery of carbon nanotubes in 1991 by Iijima, there has been great interest in creating long, continuous nanotubes for applications where their properties coupled with extended lengths will enable new technology developments. For example, ultralong nanotubes can be spun into fibres that are more than an order of magnitude stronger than any current structural material, allowing revolutionary advances in lightweight, high-strength applications. Long metallic nanotubes will enable new types of micro-electromechanical systems such as micro-electric motors, and can also act as a nanoconducting cable for wiring micro-electronic devices. Here we report the synthesis of 4-cm-long individual single-wall carbon nanotubes (SWNTs) at a high growth rate of 11 microm s(-1) by catalytic chemical vapour deposition. Our results suggest the possibility of growing SWNTs continuously without any apparent length limitation.

[001] zone-axis bright-field diffraction contrast from coherent Ge(Si) islands on Si(001)

Coherent Ge(Si)/Si(001) quantum dot islands grown by solid source molecular beam epitaxy at a growth temperature of 700 degrees C were investigated using transmission electron microscopy working at 300kV. The [001] zone-axis bright-field diffraction contrast images of the islands show strong periodicity with the change of the TEM sample substrate thickness and the period is equal to the effective extinction distance of the transmitted beam. Simulated images based on finite element models of the displacement field and using multi-beam dynamical diffraction theory show a high degree of agreement. Studies for a range of electron energies show the power of the technique for investigating composition segregation in quantum dot islands.

Formation of pile networks by long carbon nanotubes from decomposition of CO on Co-Mo film

We report the formation of pile networks by long carbon nanotubes grown at 700 degrees C from a Co-Mo film on a quartz plate. Carbon monoxide (CO) was used as the carbon source. The networks were formed because the density of catalyst particles on the substrate was low, which resulted in low carbon nanotube density that did not support vertical growth. At the same time, the low carbon nanotube density makes it possible for CO to reach the catalysts on the substrate for continuous growth. No obvious amorphous carbon chunks were observed, suggesting that the pile networks consisted of fairly high-quality, long carbon nanotubes.

Structural Model of the Orthorhombic Non-Fibonacci Approximant in the Al12Fe2Cr Alloy

Al5.103(Fe, Cr), orthorhombic, Imm2, a = 12.34, b = 12.41, c = 30.71 Å, V = 4701 Å3, atoms/cell = 305 (average), D x \simeq 3.4 g cm−3. A structural model of the non-Fibonacci approximant O-AIFeCr with composition Al5.103(Fe, Cr) found in an Al12Fe2Cr alloy has been derived from its high-resolution electron microscopy images and the structure of the hexagonal \mu-Al4Mn [Shoemaker, Keszler & Shoemaker (1989). Acta Cryst. B45, 13–20], being isostructural to \mu-Al4Cr. Among the 14 unique positions of transition metal (TM) atoms, 13 are icosahedrally coordinated: five of these icosahedra interpenetrate into each other, forming icosahedral chains along [010], and the remaining eight icosahedra with their twofold axis parallel to this axis. This structural model describes a (010) layer structure with a sequence P^{m}FP(P^{m}FP)_I, where a flat layer F (a mirror plane) is sandwiched between two puckered P and P m layers, and (P^{m}FP)I is related to P^{m}FP through a body-centred translation. The interatomic distances are 2.51–2.74 Å for TM—TM, 2.38–2.99 for TM—Al and 2.41–3.18 Å, for Al—Al. Simulated images and electron diffraction patterns calculated based on this structural model are comparable with the experimentally observed results.

[Pharmacological study on Asparagus officinalis Linn]

Our experiment shows that Asparagus officinalis can increase the clearance rate of charcoal particles and the weight of immune organs in mice, and thus helps to facilitate their antifatigue, anoxia tolerance, analgesia and memory improvement, as well as decrease the contents of lipid peroxide (LPO) in plasma, liver and brain of the animal.