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The present study assessed the effects of vegetarian and omnivorous diets on HDL-cholesterol (HDL-C), LDL-cholesterol (LDL-C), TAG and the ratio of HDL-C to total cholesterol (TC) by gender.
HDL-C, LDL-C, TAG and HDL-C:TC were compared among three diet groups (vegan, ovo-lacto vegetarian and omnivorous). Multivariate linear regression analysis was performed to examine factors significantly and independently associated with vegetarian status and to estimate the β value of lipid profiles for the diet groups.
A cross-sectional study. Data were obtained from the Taiwanese Survey on the Prevalence of Hyperglycemia, Hyperlipidemia and Hypertension (TwSHHH).
The study comprised included 3257 men and 3551 women.
After adjusting for confounders, vegan and ovo-lacto vegetarian diets lowered LDL-C levels (β=−10·98, P=0·005 and β=−7·12, P=0·025, respectively) in men compared with omnivorous diet. There was a significant association between HDL-C and vegan diet (β=−6·53, P=0·004). In females, the β values of HDL-C, TAG and HDL-C:TC were −5·72 (P<0·0001), 16·51 (P=0·011) and −0·02 (P=0·012) for vegan diet, and −4·86 (P=0·002), 15·09 (P=0·008) and −0·01 (P=0·026) for ovo-lacto vegetarian diet, when compared with omnivorous diet.
Vegan diet was associated with lower HDL-C concentrations in both males and females. Because the ovo-lacto vegetarian diet was effective in lowering LDL-C, it may be more appropriate for males.
Carbon/carbon composites (C/C composites) possess superior characteristics of low density, high strength, extremely low coefficient of thermal expansion, high fatigue resistance. In carbonization process, the high temperature pyrolysis made of carbon, hydrogen, oxygen and other elements, results in a lot of voids and cavities generated in the interior of C/C composites. Therefore, the C/C composites are densified to fill the void by using repeated impregnation. But densification is a time-wasting and complex process, which increases production costs in the manufacturing process.
In this study, the Multi-Wall Carbon Nanotubes (MWNTs) were adopted as reinforcement material for C/C composites to reduce the existence of voids or cavities and enhance the mechanical properties of C/C composites under environment aging effects. Three different temperature with high moisture conditions are used to be tested, including high temperature (150°C/ 90%RH), room temperature (25°C/90%RH), and low temperature (-15°C/90%RH) to analyze the mechanical properties of C/C composites, such as flexural and Interlaminar Shear Strength (ILSS).
The surface modification of carbon nanotubes（CNTs）has been recently observed to influence the distribution of CNTs in epoxy resin and the mechanical properties and electrical conductivities of these CNTs. Accordingly, the treatment of CNTs with organic acids to oxidize them generates functional groups on the surface of CNTs. This investigation studies the consequent enhancement of the mechanical properties and electrical conductivities of CNTs. The influence of adding various proportions of CNTs to the epoxy resin on the mechanical properties and electrical conductivities of the composites thus formed is investigated, and the strength of the material is tested at different temperatures. Moreover, the creep behavior of carbon fiber （CF）/epoxy resin thermosetting composites was tested and analyzed at different temperatures and stresses. The creep exhibits only two stages- primary creep and steady-state creep. The effects of creep stress, creep time, and humidity on the creep of composites that contain various proportion of CNTs were investigated at various temperatures.
Creep strain is believed to increase with applied stress, creep time, humidity, and temperature. It also increases as hardness decrease. The test results also indicate that mechanical strength and electrical conductivity increase with the amount of CNTs added to the composites. Different coefficients of expansion of the matrix, fiber and CNTs, are such that overexpansion of the matrix at high temperature results in cracking in it. An SEM image of the fracture surface reveals debonding and the pulling out of longitudinal fibers because of poor interfacial bonding between fiber and matrix, which reduce overall strength.
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