A Study on the Factors That Influence the Acoustic Performance of a Steel Stud Wall Assembly

With the recent introduction of light gauge steel framing systems in the concrete-dominated Korean construction industry, more buildings are built with drywall that is mainly composed of steel studs and gypsum boards. While load-bearing steel studs are extensively applied in residential construction, nonload-bearing steel studs are applied in various building fields such as commercial, educational, as well as residential. As building projects involving steel stud walls are becoming to increase, higher demands in performance are requested from architects and builders, especially in the field of sound performance. A series of acoustic test were performed in the nationally certified sound-testing laboratory at Korean Institute of Construction Technology (KICT) in order to evaluate and analyze factors that influence acoustic performance of steel stud wall assemblies. Factors affecting the acoustic performance of steel stud walls that are analyzed in this paper include among others, the composition and structure of steel studs, stud spacing, stud thickness, stud size, use of resilient channel, screw spacing, etc. Factors relating to gypsum boards that were tested as part of the evaluation of acoustic performance are not included in this paper. Results of this study, which is co-funded by 3 major gypsum board companies in Korea, are being used to develop stud wall assemblies that meet the required acoustic performance for unit-to-unit separating walls, as well as present architects and builders with a better understanding on the sound behavior of steel stud drywall

Effect of Conjugated Linoleic Acid Feeding on the Growth Performance and Meat Fatty Acid Profiles in Broiler: Meta-analysis

The effect of conjugated linoleic acid (CLA) feeding on growth performance and fatty acid profiles in thigh meat of broiler chicken was investigated using meta-analysis with a total of 9 studies. Overall effects were calculated by standardized mean differences between treatment (CLA fed) and control using Hedges’s adjusted g from fixed and random effect models. Meta-regression was conducted to evaluate the effect of CLA levels. Subgroups in the same study were designated according to used levels of CLA, CP levels or substituted oils in diets. The effects on final body weight, weight gain, feed intake and feed conversion ratio were investigated as growth parameters. Total saturated and unsaturated fatty acid concentrations and C16:0, C18:0, C18:2 and C18:3 concentrations in thigh meat of broiler chicken were used as fatty acid profile parameters. The overall effect of CLA feeding on final weight was negative and it was only significant in fixed effect model (p<0.01). Significantly lower weight gain, feed intake and higher feed conversion ratio compared to control were found (p<0.05). CLA feeding on the overall increased total saturated fatty acid concentration in broilers compared to the control diet (p<0.01). Total unsaturated fatty acid concentration was significantly decreased by CLA feeding (p<0.01). As for individual fatty acid profiles, C16:0, C18:0 and C18:3 were increased and C18:2 was significantly decreased by CLA feeding (p<0.01). In conclusion, CLA was proved not to be beneficial for improving growth performance, whereas it might be supposed that CLA is effective modulating n-6/n-3 fatty acids ratio in thigh meat. However, the economical compensation of the loss from suppressed growth performance and increased saturated fatty acids with the benefit from enhanced n-6/n-3 ratio should be investigated in further studies in order to propose an appropriate use of dietary CLA in the broiler industry

Comparative studies of meat quality traits and the proteome profile between low pH and high pH muscles in longissimus dorsi of Berkshire

This study was conducted to assess the molecular mechanism of meat quality between low and high pH muscles using two-dimensional gel electrophoresis (2DE) with matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF/MS) on longissimus dorsi (LD) muscles from Berkshire species, assigned to high (5.92 ± 0.02) and low pH groups (5.55 ± 0.03). The higher pH group had a lower lightness, yellowness, drip loss, shear force, and a higher NPPC (national pork producers council) color than the low pH group. The meat quality changes were related to the altered protein expression between the two groups. Fourteen protein spots were identified by MALDI-TOF/MS and among them, nine proteins involved in meat quality attributes significantly increased: the alpha-crystallin B chain (CRYAB), dual specificity phosphatase 1 (DUSP1), vimentin (VIM) X1 and X2, ATP synthase subunit d, mitochondrial (ATP5H), peroxiredoxin6 (PRDX6), ubiquitin carboxyl-terminal hydrolase14 (UCTH14), and cytochrome c (cyt c). Moreover, the proteins’ translation efficiency was analyzed by their mRNA expression via qPCR. An increase in the mRNA levels of ATP5H, PRDX6, and UCTH14 is consistent with protein expressions. These results may provide valuable information to decipher the molecular mechanism behind meat quality of low and high pH muscles.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author