Enhancing Thermal Conductivity of hBN/SiC/PTFE Composites with Low Dielectric Properties via Pulse Vibration Molding.

In order to enhance the thermal conductivity of polytetrafluoroethylene (PTFE)-based composites, while maintaining relatively low dielectric constant and dielectric loss for high-frequency and high-speed applications, hexagonal boron nitride (hBN) and silicon carbide (SiC) compounded fillers are filled into the PTFE matrix. The hBN/SiC/PTFE composites are prepared by pulse vibration molding (PVM), and their subsequent thermal conductivities are comparatively investigated. The PVM process with controlled fluctuation in pressure (1 Hz square wave force, 0-20 MPa, at 150 °C) can reduce the sample porosity and surface defects, improve the orientation of hBN, and increase the thermal conductivity by 44.6% compared with that obtained by compression molding. When hBN:SiC (vol) is 3:1, the in-plane thermal conductivity of the composite with 40 vol% filler content is ≈4.83 W m-1  K-1 , which is 40.3% higher than that of hBN/PTFE. Regarding the dielectric properties, hBN/SiC/PTFE maintains a low dielectric constant of 3.27 and a low dielectric loss of 0.0058. The dielectric constants of hBN/SiC/PTFE ternary composites are predicted by using different prediction models, among which the effective medium theory (EMT), is in good agreement with the experimental results. PVM shows great potential in the large-scale preparation of thermal conductive composites for high-frequency and high-speed applications.

Hsa-miRNA-143-3p regulates the odontogenic differentiation of human stem cells from the apical papilla by targeting NFIC.

AIM: To evaluate the effects of hsa-miRNA-143-3p on the cytodifferentiation of human stem cells from the apical papilla (hSCAPs) and the post-transcriptional regulation of Nuclear factor I-C (NFIC). METHODOLOGY: miRNA expression profiles in human immature permanent teeth and during hSCAP differentiation were examined. hSCAPs were treated with miR-143-3p overexpression or silencing viruses, and the proliferation and odontogenic and osteogenic differentiation of these stem cells, and the involvement of the NFIC pathway, were investigated. Luciferase reporter and NFIC mutant plasmids were used to confirm NFIC mRNA as a direct target of miR-143-3p. NFIC expression analysis in the miR-143-3p overexpressing hSCAPs was used to investigate whether miR-143-3p functioned by targeting NFIC. Student's t-test and chi-square tests were used for statistical analysis. RESULTS: miR-143-3p expression was screened by microarray profiling and was found to be significantly reduced during hSCAP differentiation (p < .05). Overexpression of miR-143-3p inhibited the mineralization of hSCAPs significantly (p < .05) and downregulated the levels of odontogenic differentiation markers (NFIC [p < .05], DSP [p < .01] and KLF4 [p < .01]), whereas silencing of miR-143-3p had the opposite effect. The luciferase reporter gene detection and bioinformatic approaches identified NFIC mRNA as a potential target of miR-143-3p. NFIC overexpression reversed the inhibitory effect of miR-143-3p on the odontogenic differentiation of hSCAPs. CONCLUSIONS: miR-143-3p maintained the stemness of hSCAPs and modulated their differentiation negatively by directly targeting NFIC. Thus, inhibition of this miRNA represents a potential strategy to promote the regeneration of damaged tooth roots.

Nuclear factor I-C expression pattern in developing teeth and its important role in odontogenic differentiation of human molar stem cells from the apical papilla.

Nuclear factor I-C (NFIC) has an important role in the development of murine dental roots, but its role in human root formation is unreported. We thus elucidated the regulatory role of NFIC in the differentiation of human stem cells from the apical papilla (hSCAPs). The first step for this was to determine the expression of NFIC in human teeth, and it was found that NFIC expression was restricted to the odontoblasts and preodontoblasts of the developing molars of humans and mice. NFIC was found to be expressed in odontoblast-like cells after the subcutaneous transplantation of hSCAPs. NFIC expression was concomitant with dentin sialophosphoprotein (DSPP) in the mineralization of hSCAPs. NFIC knockdown in hSCAPs significantly inhibited expression of DSPP and promoted that of dentin matrix protein 1 (DMP1), meanwhile upregulated the expression of TGF-ß1 and downregulated SMAD3 and SMAD4. NFIC expression was significantly upregulated after TGF-ß1 treatment in hSCAPs. NFIC knockdown prolonged G1 phase of the cell cycle, but had no effect on cell proliferation and migration. These results suggest that NFIC is involved in the development of human root dentin and the regulation of odontoblastic differentiation of hSCAPs. NFIC may participate in the DMP1-DSPP signaling pathway and comprises a complex signaling cycle with TGF-ß1.

Role of Candida albicans-secreted aspartyl proteinases (Saps) in severe early childhood caries.

Candida albicans is strongly associated with severe early childhood caries (S-ECC). However, the roles of secreted aspartyl proteinases (Saps), an important virulence factor of C. albicans, in the progress of S-ECC are not clear. In our study, the Saps activities were evaluated by the yeast nitrogen base-bovine serum albumi (YNB-BSA) agar plate method and by the MTT method with bovine serum albumin (BSA) as the substrate. Genotypes of C. albicans and gene expression of Sap1-5 were evaluated. The relationships of Saps activities and genotypes with S-ECC were analyzed. The results showed that enzyme activities of Saps in the S-ECC group were significantly higher than those in the caries free (CF) group (p<0.05). Genotypes A, B and C were detected in the S-ECC group, and genotypes A and C were detected in the CF group. In the genotype A group, Saps activity in the S-ECC group was significantly different from that in the CF group (p<0.05). The gene expression level of Sap1 in the S-ECC group was significantly higher than that in the CF group (p=0.001), while Sap4 expression was significantly lower than that in the CF group (p=0.029). It can be concluded that Sap1-5 are the predominant proteinase genes expressed in C. albicans from dental biofilm and Sap1 may play an important role in the development of S-ECC.

Nanoplastic pollution changes the intestinal microbiome but not the morphology or behavior of a freshwater turtle.

Humans produce 350 million metric tons of plastic waste per year, leading to microplastic pollution and widespread environmental contamination, particularly in aquatic environments. This subsequently impacts aquatic organisms in myriad ways, yet the vast majority of research is conducted in marine, rather than freshwater systems. In this study, we exposed eggs and hatchlings of the Chinese soft-shelled turtle (Pelodiscus sinensis) to 80-nm polystyrene nanoplastics (PS-NPs) and monitored the impacts on development, behavior and the gut microbiome. We demonstrate that 80-nm PS-NPs can penetrate the eggshell and move into developing embryos. This led to metabolic impairments, as evidenced by bradycardia (a decreased heart rate), which persisted until hatching. We found no evidence that nanoplastic exposure affected hatchling morphology, growth rates, or levels of boldness and exploration, yet we discuss some potential caveats here. Exposure to nanoplastics reduced the diversity and homogeneity of gut microbiota in P. sinensis, with the level of disruption correlating to the length of environmental exposure (during incubation only or post-hatching also). Thirteen core genera (with an initial abundance >1 %) shifted after nanoplastic treatment: pathogenic bacteria increased, beneficial probiotic bacteria decreased, and there was an increase in the proportion of negative correlations between bacterial genera. These changes could have profound impacts on the viability of turtles throughout their lives. Our study highlights the toxicity of environmental NPs to the embryonic development and survival of freshwater turtles. We provide insights about population trends of P. sinensis in the wild, and future directions for research.

Prevalence and risk factors of children's dental anxiety in China: a longitudinal study.

OBJECTIVES: Dental anxiety remains widespread among children, may continue into adulthood and affect their oral health-related quality of life and clinical management. The aim of the study was to explore the trend of children's dental anxiety over time and potential risk factors. DESIGN: Longitudinal study. METHODS: Children aged between 5 and 12 years were investigated with the Chinese version of face version of Children's Fear Survey Schedule-Dental Subscale (CFSS-DS) and Frankl Behavior Rating scale from 2008 to 2017, and influential factors were explored. RESULTS: Clinical data were available from 1061 children, including 533 (50.2%) male participants and 528 (49.8%) female participants. The total CFSS-DS scores ranged from 16 to 66, with a mean of 24.8±10.3. The prevalence of dental anxiety is 11.59%. No significant differences in total CFSS-DS scores between girls and boys were found. According to the Frankl scale, 238 children were allocated to the uncooperative group and the remaining 823 children were allocated to the cooperative group. Scores of CFSS-DS were negatively correlated with the clinical behaviour level of Frankl. Children aged 11-12 years old had significantly decreased scores compared with other age groups, and there was a decline in the scores of the group aged 8-10 years old over time. The factor analysis divided 15 items of CFSS-DS into four factors, and the total scores of 'less invasive oral procedures' items belonging to factor III decreased significantly over time in the group aged 8-10 years old. CONCLUSIONS: Age is a significant determinant for children's dental anxiety, and dental anxiety outcomes have improved for Chinese children aged 8-10 years. This study is one of the few reports on changes of children's dental anxiety in a new era of information, but the results may be extrapolated to other populations with caution.

Bioinspired Multiresonant Acoustic Devices Based on Electrospun Piezoelectric Polymeric Nanofibers.

Cochlear hair cells are critical for the conversion of acoustic into electrical signals and their dysfunction is a primary cause of acquired hearing impairments, which worsen with aging. Piezoelectric materials can reproduce the acoustic-electrical transduction properties of the cochlea and represent promising candidates for future cochlear prostheses. The majority of piezoelectric hearing devices so far developed are based on thin films, which have not managed to simultaneously provide the desired flexibility, high sensitivity, wide frequency selectivity, and biocompatibility. To overcome these issues, we hypothesized that fibrous membranes made up of polymeric piezoelectric biocompatible nanofibers could be employed to mimic the function of the basilar membrane, by selectively vibrating in response to different frequencies of sound and transmitting the resulting electrical impulses to the vestibulocochlear nerve. In this study, poly(vinylidene fluoride-trifluoroethylene) piezoelectric nanofiber-based acoustic circular sensors were designed and fabricated using the electrospinning technique. The performance of the sensors was investigated with particular focus on the identification of the resonance frequencies and acoustic-electrical conversion in fibrous membrane with different size and fiber orientation. The voltage output (1-17 mV) varied in the range of low resonance frequency (100-400 Hz) depending on the diameter of the macroscale sensors and alignment of the fibers. The devices developed can be regarded as a proof-of-concept demonstrating the possibility of using piezoelectric fibers to convert acoustic waves into electrical signals, through possible synergistic effects of piezoelectricity and triboelectricity. The study has paved the way for the development of self-powered nanofibrous implantable auditory sensors.

Impact of oral health behaviors on dental caries in children with intellectual disabilities in Guangzhou, China.

Dental care is consistently reported as one of the primary medical needs of children with disabilities (IDC). The aim of the present study was to explore the influence of oral health behaviors on the caries experience in children with intellectual disabilities in Guangzhou, China. A cross-sectional study was carried out in 477 intellectually disabled children, 12 to 17 years old, who were randomly selected from special educational schools in Guangzhou. A self-administered parental questionnaire was used to collect data on socio-demographic characteristics and oral health behavior variables, and 450 valid questionnaires were returned. Multiple regression analysis was used to examine the factors associated with dental caries. The average age of those in the sample was 14.6 years (SD = 1.3), 68.4% of whom were male, and the caries prevalence rate was 53.5% (DMFT = 1.5 ± 2.0). The factors significantly affecting the development of dental caries in IDC included gender, the presence or absence of cerebral palsy, and the frequency of dental visits and toothbrushing. In conclusion, the presence of cerebral palsy contributed to an increase risk of caries experience in intellectually disabled children, while toothbrushing more than twice a day and routine dental visits were caries-protective factors. Oral health promotion action may lead to a reduction in dental caries levels in IDC.