Determining surface structure and stability of ε-Fe2C, χ-Fe5C2, θ-Fe3C and Fe4C phases under carburization environment from combined DFT and atomistic thermodynamic studies

The chemical–physical environment around iron based FTS catalysts under working conditions is used to estimate the influences of carbon containing gases on the surface structures and stability of ε-Fe2C, χ-Fe5C2, θ-Fe3C and Fe4C from combined density functional theory and atomistic–thermodynamic studies. Higher carbon content gas has higher carburization ability; while higher temperature and lower pressure as well as higher H2/CO ratio can suppress carburization ability. Under wide ranging gas environment, ε-Fe2C, χ-Fe5C2 and θ-Fe3C have different morphologies, and the most stable non-stoichiometric termination changes from carbon-poor to carbon-rich (varying surface Fe/C ratio) upon the increase in ΔμC. The most stable surfaces of these carbides have similar surface bonding pattern, and their surface properties are related to some common phenomena of iron based catalysts. For these facets, χ-Fe5C2-(100)-2.25 is most favored for CO adsorption and CH4 formation, followed by θ-Fe3C-(010)-2.33, ε-Fe2C-(121)-2.00 and Fe4C-(100)-3.00, in line with surface work function and the charge of the surface carbon atoms

Impact of human papillomavirus vaccine on cervical cancer epidemic: Evidence from the surveillance, epidemiology, and end results program

IntroductionSince 2006, the human papillomavirus (HPV) vaccine has been recommended for females aged 9–26 years in the United States. Aiming to evaluate the early effect of the HPV vaccine on cervical cancer, this study assessed the incidence of cervical cancer by age and histology before and after the introduction of HPV vaccination.MethodsData on cervical cancer incidence from 1975–2019 were extracted from the Surveillance, Epidemiology, and End Results Program. Joinpoint regression was used to determine temporal trends over time. Future cervical cancer incidence (2015–2039) was projected using Bayesian age-period-cohort analysis. Age-period-cohort (APC) models were created to evaluate age, period, and cohort effects.ResultsFor overall cervical cancer and cervical squamous cell carcinoma (SCC), incidence rate showed decreasing trends (–0.7%, and –1.0% annually, respectively), whereas cervical adenocarcinoma (AC) incidence continuously increased (2.6% annually). The incidence trends for AC were stable in the 20–24 and 25–29-year age groups, whereas there was an increasing trend in older age groups. Similarly, the projected trend for AC in females aged 20–30 years exhibited a decline, whereas an increase was predicted in the 31–40–year age group, especially in the 35–44 year age group. The birth cohort and period effects in SCC and AC were extracted from APC models.DiscussionDuring the period of 1975–2019, the incidence of cervical AC remained almost unchanged in the age groups receiving HPV vaccines while increased in the age groups not receiving HPV vaccines. The birth cohort effects of SCC and AC of the cervix provided evidence supporting the effectiveness of the HPV vaccine in preventing cervical cancer

护理学生临床实习前锐器伤预防的认知情况调查研究

Objective: To investigate the cognition of sharp injury prevention among nursing students before the clinical practice in order to provide a basis for corresponding measures and active measures. Methods: In July 2014, a total of 232 nursing students in 3 A grade Hospital of Guangzhou, from 30 colleges and universities of 8 provinces, were tested by self-made questionnaire in regard to sharp injury prevention knowledge. Results: The awareness rate of occupational exposure, occupational exposure prevention, Guideline for prevention and control for occupational exposure to bloodborne pathogen by National Health and Family Planning Commission 2009 was 28.94% and 13.71%, 1.01%; and the highest score of sharp instrument injury prevention knowledge was 22 points, the lowest score was 4 points, with an average of 15.92 ± 2.59 points. Sharp injury knowledge gained from school education accounts for 87.31%, but the students who have not received relevant education accounts for 3.05%. Conclusion: The overall situation of occupational exposures cognition is not optimistic, the master of sharp instrument injury prevention knowledge is not complete; and related curriculum in part of the schools is unreasonable, or receives poor effect. Some schools need to adjust the curriculum, strengthen the prevention knowledge of sharp injuries, occupational exposure to bloodborne pathogen. Hospitals need to strengthen pre-job training of nursing students and strengthen the clinical teaching work. Schools and hospitals need to jointly explore teaching mode for nursing students, so as to promote the students to master the sharp instrument injury prevention knowledge, the implementation of relevant measures of protection, and ensure the safety of students and patients. 目的  对护理学生临床实习前锐器伤预防的认知情况进行了解，以便为采取积极有效的应对措施提供依据。方法  采用自行编制问卷对2014年7月广州市某三甲医院来自全国8省30所高等院校的232名护理实习学生的一般资料和锐器伤认知情况进行调查并分析。结果  职业暴露、职业暴露后预防、国家卫计委2009《血源性病原体职业接触防护导则》知晓率为28.94%、13.71%、1.01%；锐器伤预防知识最高得分22分，最低得分4分，均数为（15.92±2.59）分。锐器伤知识来源于学校教育为87.31%，而未接受过相关教育者为3.05%。结论  研究对象对职业暴露认知总体情况不容乐观；锐器伤预防知识掌握不全；部分学校相关课程设置不合理或教育效果欠佳。部分学校需调整课程设置，加强锐器伤预防、血源性病原体职业接触防护等相关知识的教育，医院需强化护理实习生岗前培训，加强临床带教工作，学校与医院需探讨共同教导护理实习学生模式，从而促进学生掌握锐器伤预防相关知识，落实相关防护措施，保障患者和学生的安全

Evidence of spin density waves in La3_3Ni2_2O7−δ_{7-\delta}

The recently discovered superconductivity with critical temperature $T_{c}$ up to 80 K in the Ruddlesden-Popper phases La$_3$Ni$_2$O$_{7-\delta}$ under pressure has drawn great attention. Here we report the positive muon spin relaxation ($\mu^+$SR) study of polycrystalline La$_3$Ni$_2$O$_{7-\delta}$ under ambient pressure. The zero-field $\mu^+$SR experiments reveal the existence of static long range magnetic order in La$_3$Ni$_2$O$_{7-\delta}$, and the the muon spin depolarization spectra are consistent with the spin density wave internal field distribution. The weak transverse field $\mu^+$SR measurements suggest the bulk magnetic transition near $T_{\rm{N}}=148$ K. This is the first research which discovers the existence of the spin density wave in La$_3$Ni$_2$O$_{7-\delta}$ microscopically

Repellent activity of Glycosmis plant extracts against two stored product insects

In the present study, the repellent activities of the leaf and/or stem crude extracts of Glycosmis lucida Wall. ex Huang, G. craibii var. glabra, G. craibii Tanaka, G. oligantha Huang, G. pentaphylla (Retz) Correa. and G. esquirolii (Levl.) Tanaka were analyzed by using assays on petri dishes against Tribolium castaneum and Liposcelis bostrychophila. The leaf and stem extracts of G. lucida, G. craibii var. glabra, G. craibii Tanaka, G. oligantha and G. esquirolii possessed significant repellent activities against T. castaneum, the same level repellent with the positive control, DEET. However, the extracts of G. pentaphylla, no repellency but some insect attractant was observed. Moreover, they also showed repellent activities against L. bostrychophila. These results indicate that extracts from G. lucida and G. oligantha leaf could be a source of novel repellent against insects

Dirac semimetal PdTe2 temperature-dependent quasiparticle dynamics and electron-phonon coupling

Dirac semimetal PdTe2 single-crystal temperature-dependent ultrafast carrier and phonon dynamics were studied using ultrafast optical pump-probe spectroscopy. Two distinct carrier and coherent phonons relaxation processes were identified in the 5 K - 300 K range. Quantitative analysis revealed a fast relaxation process ({\tau}_f) occurring on a subpicosecond time scale which originated from electron-phonon thermalization. This was followed by a slower relaxation process ({\tau}_s) with a time scale of ~ 7-9.5 ps which originated from phonon-assisted electron-hole recombination. Two significant vibrational modes resolved at all measured temperatures and corresponded to Te atoms in-plane (E_g), and out-of-plane (A_1g), motion. As temperature increased both phonon modes softened markedly. A_1g mode frequency monotonically decreased as temperature increased. Its damping rate remained virtually unchanged. As expected, E_g decreased uniformly as temperatures rose. At temperatures above 80 K, there was insignificant change. Test results suggested that pure dephasing played an important role in the relaxation processes. PdTe2 phonon is thought responsible for its superconductive properties. Examining phonons behavior should improve the understanding of its complex superconductivity.Comment: 6 pages, 4 figure