Shaoru Zhang

Silicane nanoribbons: electronic structure and electric field modulation

We present electronic band structure, Gibbs free energy of formation, and electric field modulation calculations for silicane nanoribbons (NRs), i.e., completely hydrogenated or fluorinated silicene NRs, using density functional theory. We find that although the completely hydrogenated silicene (H-silicane) sheet in the chair-like configuration is an indirect-band-gap semiconductor, a direct band gap can be achieved in the zigzag H-silicane NRs by using Brillouin-zone folding. Compared to H-silicane NRs, the band gaps of completely fluorinated silicene (F-silicane) NRs reduce at least by half. For all silicane NRs considered here, the Gibbs free energy of formation is negative but shows different trends by changing the ribbon width for H-silicane NRs and F-silicane NRs. Furthermore, by analyzing the effect of transverse electric fields on the electronic properties of silicane NRs, we show that an external electric field can make the electrons and holes states spatially separated and even render silicane NRs self-doped. The tunable electronic properties of silicane NRs make them suitable for nanotechnology application.

Improving detection and notification of tuberculosis cases in students in Shaanxi province, China: an intervention study.

BackgroundCooperation between different public and private health institutes involved in tuberculosis (TB) control has proven to enhance TB control in different settings. In China, such a mechanism has not been set up yet between Centers for Disease Control (CDCs) and university hospitals despite an increased TB incidence among students. This study aims to improve arrival of TB suspects identified by universities at the CDCs in order to manage them under standardized, directly observed treatment-short course (DOTS) conditions according to the National Tuberculosis Programme (NTP) guidelines.MethodsFive matched pairs of universities were randomly assigned to the control and intervention group. After a baseline survey, a cooperation mechanism between local CDCs and university hospitals was set up in the intervention group. The effects on referral of TB suspects to the local CDC, tracing by the local CDC, and arrival at the local CDCs were assessed. Differences were tested by means of the chi-square test.ResultsDuring the baseline survey, the referral, tracing and arrival rates were between 37% and 46%. After implementation of the cooperation mechanism, these rates had not changed in the control group but increased significantly in the intervention group: the referral, tracing and arrival rates were 97%, 95%, and 93%, respectively.ConclusionsIt is feasible and effective to set up cooperation between CDCs and university hospitals to increase the number of TB suspects examined by CDCs and increase the number of TB patients treated under DOTS conditions. These public-public mix (PPM) activities should be expanded to cover all other university hospitals in China.

Band gap engineering of ZnSnN2/ZnO (001) short-period superlattices via built-in electric field

Using density-functional-theory calculations combined with hybrid functional, we investigate the band gaps and built-in electric fields of ZnSnN2/ZnO (001) short-period superlattices. The band gap of ZnSnN2/ZnO (001) superlattice can be tuned from 1.9 eV to 0 eV by varying the thickness of both the ZnSnN2 and ZnO regions. Compared to the III-nitride superlattices, stronger built-in electric fields, induced by the polarizations, form inside the ZnSnN2/ZnO superlattices. The lowest electron and uppermost hole states are mainly localized at the two opposite interfaces of the superlattice, but the tails of the lowest electron states extend over several atomic layers. Based on the electrostatic argument, we demonstrate that variations of the band gap are approximately described by a geometric factor. The influence of the in-plane strain is also discussed. The results will be valuable in the design of ZnSnN2/ZnO heterostructures for electronics and optoelectronics applications.

Magnetism from 2p states in K-doped ZnO monolayer: A density functional study

Using density-functional–based methods, we have studied 2p-based magnetic moments and magnetic coupling in potassium (K)-doped ZnO monolayer. We find that the substitution of a K atom at a Zn site in a ZnO monolayer induces a magnetic moment of per cell mainly originating from the O-2p states and has much lower formation energy than a magnetic Zn vacancy. A half-metallic electronic property and long-range ferromagnetic coupling between the magnetic moments are obtained based on the generalized gradient approximation (GGA) calculations, which is explained by a double-exchange–like mechanism. Moreover, with stronger correlation correction on 2p states, the structure of the substitutional K impurity undergoes a Jahn-Teller–like distortion. Incorporating magnetism into a two-dimensional ZnO monolayer will promote its application in nanodevices.

Barriers to tuberculosis control and prevention in undergraduates in Xi’an, China: A qualitative study

To understand the barriers to tuberculosis (TB) control and prevention in undergraduate students and to propose the strategies to improve this work, we conducted in-depth interviews with three groups of individuals in infirmaries of universities and colleges, TB departments of district Centers for Disease Control and Prevention (CDCs), and undergraduates with TB. The study identified four major themes: inadequate workforce and less than optimal functioning of infirmaries and district TB control agencies; poor cooperation in the process of discovery, treatment, and surveillance of undergraduates with TB; poor acceptance of the national TB policy; and inadequate attention to TB prevention. Failure to carry out the national TB policy was the major barrier to TB control and prevention in undergraduates. TB control agencies should strengthen the implementation of the national TB policy.

The experiences of high school students with pulmonary tuberculosis in China: a qualitative study

BackgroundClustered tuberculosis (TB) still occurred nationally in Chinese schools every year, where high school students patients accounts for the highest proportion. These young TB patients are in a critical period of physical and psychological growth. Research on their illness experience and analysis of underlying causes remains blank. The purpose of this study is to explore the overall illness experience of Chinese high school TB patients and to investigate the individual and social causes of such experience.MethodsTwenty-two high school TB patients in a certain county of Shaanxi province were interviewed in-depth twice when initial diagnosed and during intermediate treatment periods. Interview data were analyzed by framework approach.ResultsThe high school TB patients worried about interruption of studies rather than the disease. They generally showed a lack of awareness of tuberculosis, were highly dependent on parents, and received assistance from teachers and students during the treatment. Most of them did not show obvious stigma.ConclusionThe unique education system and sociocultural factors in China are the root of special illness experience of high school TB patients. Huge pressure in college entrance examination leads sick students to worry about interruption of studies more than the disease itself. Their serious lack of awareness of TB, caused by the ignorance of school, parents and the students, becomes the biggest obstacle to timely diagnosis and treatment. Whether high dependence on parents is conducive to disease recovery varies with each individual. Meanwhile, patients’ weak stigma could play a positive role in disease recovery. Educational and medical institutions should develop more effective TB control strategies based on these factors.

Development and psychometric testing of the Knowledge, Attitudes and Practices (KAP) questionnaire among student Tuberculosis (TB) Patients (STBP-KAPQ) in China

BackgroundTB outbreaking in schools is extremely complex, and presents a major challenge for public health. Understanding the knowledge, attitudes and practices among student TB patients in such settings is fundamental when it comes to decreasing future TB cases. The objective of this study was to develop a Knowledge, Attitudes and Practices Questionnaire among Student Tuberculosis Patients (STBP-KAPQ), and evaluate its psychometric properties.MethodsThis study was conducted in three stages: item construction, pilot testing in 10 student TB patients and psychometric testing, including reliability and validity. The item pool for the questionnaire was compiled from literature review and early individual interviews. The questionnaire items were evaluated by the Delphi method based on 12 experts. Reliability and validity were assessed using student TB patients (n = 416) and healthy students (n = 208). Reliability was examined with internal consistency reliability and test-retest reliability. Content validity was calculated by content validity index (CVI); Construct validity was examined using exploratory factor analysis (EFA) and confirmatory factor analysis (CFA); The Public Tuberculosis Knowledge, Attitudes and Practices Questionnaire (PTB-KAPQ) was applied to evaluate criterion validity; As concerning discriminant validity, T-test was performed.ResultsThe final STBP-KAPQ consisted of three dimensions and 25 items. Cronbach’s α coefficient and intraclass correlation coefficient (ICC) was 0.817 and 0.765, respectively. Content validity index (CVI) was 0.962. Seven common factors were extracted by principal factor analysis and varimax rotation, with a cumulative contribution of 66.253%. The resulting CFA model of the STBP-KAPQ exhibited an appropriate model fit (χ2/df = 1.74, RMSEA = 0.082, CFI = 0.923, NNFI = 0.962). STBP-KAPQ and PTB-KAPQ had a strong correlation in the knowledge part, and the correlation coefficient was 0.606 (p < 0.05). Discriminant validity was supported through a significant difference between student TB patients and healthy students across all domains (p < 0.05).ConclusionsAn instrument, “Knowledge, Attitudes and Practices Questionnaire among Student Tuberculosis Patients (STBP-KAPQ)” was developed. Psychometric testing indicated that it had adequate validity and reliability for use in KAP researches with student TB patients in China. The new tool might help public health researchers evaluate the level of KAP in student TB patients, and it could also be used to examine the effects of TB health education.

Development and validation of college students’ tuberculosis knowledge, attitudes and practices questionnaire (CS-TBKAPQ)

BackgroundChina faces many challenges in controlling tuberculosis (TB). One significant challenge is the control of college students’ TB. In particular, cross-sectional studies of college students’ knowledge, attitudes and practices (KAP) in regard to TB have attracted substantial attention. However, few measurement tools have been developed to aid processes related to expert consultation, pre-testing, reliability and validity testing. Our study developed the College Students’ TB Knowledge Attitudes and Practices Questionnaire (CS-TBKAPQ) following the scale development steps.MethodsThe construction of the CS-TBKAPQ was based on the Theory of Knowledge, Attitude, Belief, and Practice (KABP or KAP). The item pool was compiled from literature reviews and individual interviews. The reliability validation was assessed by calculating Cronbach’s α coefficient, the split-half reliability coefficient, and the test-retest reliability coefficient. Construct validity was assessed using exploratory factor analysis (EFA) and confirmatory factor analysis (CFA). The diagnostic accuracy was evaluated using the World Health Organization Advocacy, Communication and Social Mobilization KAP Survey Questionnaire (WHO-TBKAPQ) as the reference standard.ResultsA total of 31 questionnaire items were proposed. Cronbach’s α coefficient, the split-half reliability coefficient and the test-retest reliability coefficient were 0.86, 0.78 and 0.91. Four factors that explained 62.52% of the total variance were also identified in EFA and confirmed in CFA. The CFA model fit indices were x2/df = 1.82 (p < 0.001), GFI = 0.925, AGFI = 0.900, RMR = 0.068, and RMSEA = 0.049. The CS-TBKAPQ was significantly correlated with the WHO-TBKAPQ and the Chinese Public TB KAP Questionnaire (CDC-TBKAPQ) developed by the Chinese Center for Disease Control and Prevention (r = 0.59, 0.60, p < 0.001). The receiver operating characteristics curve (ROC) analysis suggested a cut-off point of 47.5, with which the CS-TBKAPQ showed a sensitivity of 73.63% and a specificity of 80.51% in identifying students with low-level KAP. The positive and negative predictive values were 83.23% and 69.91%.ConclusionsThe findings of this study demonstrate that the CS-TBKAPQ is a reliable and valid tool for measuring the KAP towards TB in college students.