Search

The dielectric and other properties of low‐dielectric‐constant materials after heating are crucial to their performance and use, but rarely studied. In this article, sandwich‐type porous polyimide (PI) film in which porous structures located on both upper and lower surfaces of flat PI film was prepared through the simple, low‐cost and green microemulsion method. The porous structures were preserved after heating due to the usage of thermally stable fluorine‐contained PI (FPI) and PI as skeleton and substrate of the porous structure, respectively, but with the increase of pore size because of the removal of thermally unstable surfactant on the inner surface of the pores. More importantly, 2.89%–5.57% of reductions in the dielectric constant with the maintenance of low dielectric loss and water absorption and high mechanical strength were observed after heating. Therefore, the low dielectric properties of heated films were well preserved upon high humidity treatment. Moreover, the structure and properties of the heated films could be adjusted via controlling the parameters in the microemuslion method. These excellent properties after the high‐temperature treatment facilitate the application of the sandwich‐type porous PI film as dielectric materials in high‐temperature environment. [ABSTRACT FROM AUTHOR]

Simultaneous improvement in dielectric, water resistance and mechanical properties of polyimide (PI) films is critical for their practical use, but difficult to achieve. Herein, a sandwich‐type porous GO/PI film with excellent comprehensive properties was obtained through integrating a GO‐containing complex, fluorine‐containing porous structure and sandwich‐type distribution of porous structure by a simple, low‐cost and green breath figure method. With the addition of only a small amount of GO‐containing complex, a low dielectric constant of 2.21, water absorption of 0.51%, increment in dielectric constant after moisture treatment of 1.60% and high tensile strength of 113.1 MPa, tensile modulus of 1.70 GPa, with 35.39%, 79.42%, 81.81% of reduction and 17.22%, 21.43% of increase compared to PI film were shown, respectively. Moreover, these properties could be adjusted through regulating the component and porous structure by changing the parameters of breath figure method. These outstanding properties make the film a promising candidate for high‐performance low‐dielectric materials. [ABSTRACT FROM AUTHOR]

The dimensional and property stability after heating is considered to be one of the most important properties for low‐dielectric‐constant materials. Herein, porous structure contained composite PI film with porous PI structure on the surface of a flat PI film was prepared through the simple and low‐cost microemulsion method. The introduction of porous coating can significantly improve the dielectric and water resistance properties of PI film, while maintaining its good mechanical properties. More importantly, the porous structures were well preserved after heating, but with the remove of surfactant layer on the inner surface of the pores, leading to lower dielectric constants with 1.06%–3.50% of reduction and lower dielectric losses less than 0.015 with the maintenance of good water resistance and mechanical properties. Excellent durability of the low dielectric constants and low dielectric losses upon high humidity were also shown for the heated composite PI film. In addition, the morphology and properties of the composite PI film both before and after heating could be controlled through varying the fabrication conditions. These results provide valuable information for the construction of the thermally stable low‐dielectric‐constant material. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate the effects of three different natural preservatives on the microbial profile, the total volatile base nitrogen (TVB‐N), and biogenic amine contents of vacuum‐packed chilled pork during storage at 4°C. Solution A comprised of tea polyphenols, chitosan, spice extract, propolis, and nisin. Solution B comprised of clove extract, cassia bark extract, ginger juice, garlic juice, and lactobacillus fermentation solution. Solution C consisted of only lactobacillus fermentation solution. The results indicated that solution A was a good natural preservative with higher bacteria inhibitory effect and higher sensory score than B and C. Besides the effect on appealing color, solution B could inhibit microbial activity although its inhibition effect was not as good as solution A. Thus, solution A could be used as a good preservative in industry. Solution C could inhibit the initial growth of Pseudomonas and partially inhibited the growth of Enterobacteriaceae; however, the content of putrescine in the pork treated with solution C was as high as 30.14 ± 2.89 mg/kg after 21 days of storage at 4°C. Hence, solution C is not an ideal preservative for vacuum‐packed chilled pork. [ABSTRACT FROM AUTHOR]

Hearing loss is the most common sensory disorder affecting 278 million people in the world, and more than 60% of hearing loss patients can be attributed to genetic causes. Although many loci have been linked to hereditary hearing impairment, most of the causative genes have not been identified as yet. The goal of this study was to investigate the cause of dominantly inherited sensorineural all-frequency hearing loss in a six-generation Chinese family. We performed exome sequencing to screen responsible candidate genes in three family members with all-frequency hearing loss and one member with normal hearing. Sanger sequencing was employed to examine the variant mutations in the members of this family and 200 healthy persons. PCR-RFLP was performed to further confirm the nucleotide mutation. A novel missense mutation c.2389G > A (GAC → AAC) in WFS1 gene was identified, which was co-segregated with the hearing loss phenotype. No mutation was found in 200 controls and the family members with normal hearing in this site. The present study identifies, for the first time, a novel mutation in WFS1 gene that causes non-syndromic hearing loss in all, rather than in low or high, frequencies. © 2014 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]