A Bi2Te3-Filled Nickel Foam Film with Exceptional Flexibility and Thermoelectric Performance

The past decades have witnessed surging demand for wearable electronics, for which thermoelectrics (TEs) are considered a promising self-charging technology, as they are capable of converting skin heat into electricity directly. Bi2Te3 is the most-used TE material at room temperature, due to a high zT of ~1. However, it is different to integrate Bi2Te3 for wearable TEs owing to its intrinsic rigidity. Bi2Te3 could be flexible when made thin enough, but this implies a small electrical and thermal load, thus severely restricting the power output. Herein, we developed a Bi2Te3/nickel foam (NiFoam) composite film through solvothermal deposition of Bi2Te3 nanoplates into porous NiFoam. Due to the mesh structure and ductility of Ni Foam, the film, with a thickness of 160 μm, exhibited a high figure of merit for flexibility, 0.016, connoting higher output. Moreover, the film also revealed a high tensile strength of 12.7 ± 0.04 MPa and a maximum elongation rate of 28.8%. In addition, due to the film’s high electrical conductivity and enhanced Seebeck coefficient, an outstanding power factor of 850 μW m−1 K−2 was achieved, which is among the highest ever reported. A module fabricated with five such n-type legs integrated electrically in series and thermally in parallel showed an output power of 22.8 nW at a temperature gap of 30 K. This work offered a cost-effective avenue for making highly flexible TE films for power supply of wearable electronics by intercalating TE nanoplates into porous and meshed-structure materials

Attitude and practice on human papilloma virus infection and vaccination among students from secondary occupational health school: a cross-sectional study

Cervical cancer (CC) is reported as the second-most common female cancer worldwide, of which 99% is caused by persistent human papillomavirus (HPV) infection. HPV vaccine protects against HPV infection and most cases of CC, which has only been introduced for a short time in mainland China. This study aimed to evaluate the attitude and practice related to HPV infection and vaccination among students at secondary occupational health school (SOHS) in China. We conducted a cross-sectional study in Southern China where data of 2248 participants were collected through questionnaires to estimate attitude and practice of students. Only 4.1% believed they were easily infected by HPV, 38.2% were willing to receive HPV vaccine and 30.8% intended to do regular screening of HPV infection in the future. Students in the second grade (OR = 1.51, 95%CI [1.25, 1.81]) and third grade (OR = 3.99, 95%CI [2.53, 6.27]) were more willing to take HPV vaccine compared to students in the first grade. Among the non-vaccinated participants, the most frequent reason for not receiving HPV vaccine was insufficient knowledge about HPV (91.1%). Characteristics of higher grade, personal education before enrollment and academic performance, medical specialty, history of sex experience and HPV vaccine and family history of other cancers were associated with higher attitude scores (p < .05). Considering the increasing prevalence of HPV infection and the need of improvement in attitude and practice toward HPV, more education about HPV infection and vaccination should be incorporated into school curriculum

Crystallographic-Orientation-Dependent Charge Separation of BiVO4 for Solar Water Oxidation

Charge separation plays a crucial role in determining the solar-to-hydrogen conversion efficiency for photoelectrochemical water splitting. Of the factors that affect charge separation, the anisotropic charge transport property of semiconductors shows great potential in promoting charge separation, but it has received little attention. Herein, we report BiVO4 photoanodes with predominant [010] and [121] orientations and demonstrate a crystallographic-orientation-dependent charge separation of BiVO4 for solar water oxidation. We found that a [010]-orientated BiVO4 photoanode generated a photocurrent 2.9 times that of the [121]-orientated one, owing to the significantly improved charge separation. An in-depth investigation of the surface band bending by open-circuit potential and film conductivity by contacting atomic force microscopy reveals that the higher electron mobility along the [010] direction than that of [121] accounts for the improvement in charge separation. This work offers a fundamental insight into charge separation in anisotropic photoanodes for rational design of efficient photoanodes for solar energy conversion

Exposure to legacy and novel perfluoroalkyl substance disturbs the metabolic homeostasis in pregnant women and fetuses: A metabolome-wide association study

Background: Perfluoroalkyl substances (PFASs) exist extensively and several of these have been verified to be toxic. Prenatal exposure to PFASs has attracted much attention. Metabolome-wide association analyses can be used to explore the toxicity mechanisms of PFASs by identifying associated biomarkers. Objectives: To evaluate associations between the metabolites in maternal and cord serum and internal exposure to several common PFASs. Methods: Paired maternal and cord serum samples were collected from 84 pregnant women who gave birth between 2015 and 2016. Seven legacy and two novel PFASs were measured. A nontarget metabolomic method and an iterative metabolite annotation based on metabolic pathways were applied to characterize the metabolic profiles. Linear regression adjusted with the false discovery rate and covariates was used to indicate the associations. Results: A total of 279 features in maternal serum and 338 features in cord serum were identified as metabolites associated with PFAS exposure. Perfluorooctanoic acid (PFOA) and perfluorohexane sulfonic acid (PFHxS) were two PFASs associated with more metabolites, while the two novel chlorinated polyfluorinated ether sulfonic acids (Cl-PFESAs) showed less relevance to the metabolome. With pathway enrichment analysis, we found that three fatty acid metabolisms and retinol metabolism were correlated with PFAS exposure in maternal blood, and that sterol metabolism showed the correlation in both maternal serum and cord serum. Conclusions: We identified metabolites and pathways in pregnant women and fetuses associated with the exposure to several PFAS, indicating a promising application for metabolome-wide association studies. Additional research is needed to confirm causation

Assessment of Portable Chlorophyll Meters for Measuring Crop Leaf Chlorophyll Concentration

Accurate measurement of leaf chlorophyll concentration (LChl) in the field using a portable chlorophyll meter (PCM) is crucial to support methodology development for mapping the spatiotemporal variability of crop nitrogen status using remote sensing. Several PCMs have been developed to measure LChl instantaneously and non-destructively in the field, however, their readings are relative quantities that need to be converted into actual LChl values using conversion functions. The aim of this study was to investigate the relationship between actual LChl and PCM readings obtained by three PCMs: SPAD-502, CCM-200, and Dualex-4. Field experiments were conducted in 2016 on four crops: corn (<i>Zea mays</i> L.), soybean (<i>Glycine max</i> L. Merr.), spring wheat (<i>Triticum aestivum</i> L.), and canola (<i>Brassica napus</i> L.), at the Central Experimental Farm of Agriculture and Agri-Food Canada in Ottawa, Ontario, Canada. To evaluate the impact of other factors (leaf internal structure, leaf pigments other than chlorophyll, and the heterogeneity of LChl distribution) on the conversion function, a global sensitivity analysis was conducted using the PROSPECT-D model to simulate PCM readings under different conditions. Results showed that Dualex-4 had a better performance for actual LChl measurement than SPAD-502 and CCM-200, using a general conversion function for all four crops tested. For SPAD-502 and CCM-200, the error in the readings increases with increasing LChl. The sensitivity analysis reveals that deviations from the calibration functions are more induced by non-uniform LChl distribution than leaf architectures. The readings of Dualex-4 can have a better ability to restrict these influences than those of the other two PCMs

A Bi2Te3-Filled Nickel Foam Film with Exceptional Flexibility and Thermoelectric Performance

The past decades have witnessed surging demand for wearable electronics, for which thermoelectrics (TEs) are considered a promising self-charging technology, as they are capable of converting skin heat into electricity directly. Bi2Te3 is the most-used TE material at room temperature, due to a high zT of ~1. However, it is different to integrate Bi2Te3 for wearable TEs owing to its intrinsic rigidity. Bi2Te3 could be flexible when made thin enough, but this implies a small electrical and thermal load, thus severely restricting the power output. Herein, we developed a Bi2Te3/nickel foam (NiFoam) composite film through solvothermal deposition of Bi2Te3 nanoplates into porous NiFoam. Due to the mesh structure and ductility of Ni Foam, the film, with a thickness of 160 &mu;m, exhibited a high figure of merit for flexibility, 0.016, connoting higher output. Moreover, the film also revealed a high tensile strength of 12.7 &plusmn; 0.04 MPa and a maximum elongation rate of 28.8%. In addition, due to the film&rsquo;s high electrical conductivity and enhanced Seebeck coefficient, an outstanding power factor of 850 &mu;W m&minus;1 K&minus;2 was achieved, which is among the highest ever reported. A module fabricated with five such n-type legs integrated electrically in series and thermally in parallel showed an output power of 22.8 nW at a temperature gap of 30 K. This work offered a cost-effective avenue for making highly flexible TE films for power supply of wearable electronics by intercalating TE nanoplates into porous and meshed-structure materials