Effect of mattress bedding layer structure on pressure relief performance and subjective lying comfort.

Mattresses' pressure relief performance and comfort largely affect sleep quality. Mattress filling materials have been proven to affect the interface pressure distribution and comfort, but the effect of mattress structure is unclear. In this paper, the interface pressure distribution and subjective comfort of 10 subjects were assessed in the different bedding layer structures of mattresses, after mattress support performance was tested. The results show that the mattresses with bedding material hardness gradually increasing from the top layer to the bottom layer (BMH-ITTB) structure have a softer surface layer, a better support core layer, and higher fitness. This enables the mattress to achieve a better decompression effect. The low-pressure area (PAI≤0.67kPa) increased, while the high-pressure area (PAI≥2.67kPa and PAI≥4.00kPa), maximum pressure (P95), average pressure (P50), and pressure index (PI) decreased. This also enables the mattress to achieve higher subjective comfort scores.

In-Depth Analysis of the Structure and Properties of Two Varieties of Natural Luffa Sponge Fibers.

The advancement in science and technology has led to luffa sponge (LS) being widely used as a natural material in industrial application because of its polyporous structure and light texture. To enhance the utility of LS fibers as the reinforcement of lightweight composite materials, the current study investigates their water absorption, mechanical properties, anatomical characteristics and thermal performance. Hence, moisture regain and tensile properties of LS fiber bundles were measured in accordance with American Society for Testing and Materials (ASTM) standards while their structural characteristics were investigated via microscopic observation. Scanning electron microscopy (SEM) was used to observe the surface morphology and fractured surface of fiber bundles. The test results show that the special structure where the phloem tissues degenerate to cavities had a significant influence on the mechanical properties of LS fiber bundles. Additionally, the transverse sectional area occupied by fibers in a fiber bundle (SF), wall thickness, ratio of wall to lumen of fiber cell, and crystallinity of cellulose had substantial impact on the mechanical properties of LS fiber bundles. Furthermore, the density of fiber bundles of LS ranged within 385.46-468.70 kg/m³, significantly less than that of jute (1360.40 kg/m³) and Arenga engleri (950.20 kg/m³). However, LS fiber bundles demonstrated superior specific modulus than Arenga engleri.

[Frequencies of 9 bp deletion of mitochondrial DNA in ethnic Miao, Buyi and Dong from Guizhou].

OBJECTIVE: To study the frequency of a 9 bp deletion polymorphism of mitochondrial DNA (mtDNA) in ethnic Miao, Buyi and Dong populations from Guizhou province. METHODS: Polymerase chain reaction-polyacrylamide gel electrophoresis (PCR-PAGE) was used to detect the 9 bp deletion. The result was verified with DNA sequencing. RESULTS: Two polymorphisms, including a standard pattern and a short pattern (the 9 bp deletion), were found among the three ethnic groups. The frequency of short pattern in 304 males was 23.0%. Respectively, those of Miao, Buyi and Dong ethnics were 28.6%, 26.8% and 13.7%. A statistically significant difference was detected among the three groups (P<0.05). CONCLUSION: The frequencies of the 9 bp polymorphism were relatively high among ethnic Miao, Buyi and Dong populations from Guizhou, and there was a significant difference between the three.