An investigation into temperature induced degradation of the compressive strength of concrete including that under cooling phase is carried out. The paper gathers and reviews a considerable amount of test data, considering the influence of different test parameters such as initial compressive strength, aggregate type, cooling regime and specimen shape. It is found that the compressive strength of concrete at high temperature is in accordance with the model proposed in the Eurocodes for calcareous concrete. However, during cooling phase, an additional reduction of compressive strength in concrete is observed, which can be as high as 20% of the initial strength for elevated temperatures around 500°C. Finally, a generic concrete model for temperature dependent compressive strength, accounting for both growth and cooling phase of temperature is proposed. The model can be used for simulating fire response of concrete structures subjected to natural fires or for the evaluation of residual load capacity of concrete structures after fire.

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Cumulus cells of pre-pubertal domestic animals are dysfunctional, perhaps due to age-specific epigenetic events. This study was designed to determine effects of melatonin treatment of donors on methylation modification of pre-pubertal cumulus cells. Cumulus cells from germinal vesicle stage cumulus oocyte complexes (COCs) were collected from eighteen lambs which were randomly divided into control group (C) and melatonin group given an 18 mg melatonin implant subcutaneous (M). Compared to the C group, the M group had higher concentrations of melatonin in plasma and follicular fluid (p < 0.05), greater superovulation, a higher proportion of fully expanded COCs, and a lower proportion of apoptotic cumulus cells (p < 0.05). Real-time PCR results showed that melatonin up-regulated expression of genes MT1, Bcl2, DNMT1, DNMT3a and DNMT3b, but down-regulated expression of genes p53, Caspase 3 and Bax (p < 0.05). Furthermore, melatonin increased FI of FITC (global methylation level) on cumulus cells (p < 0.05). To understand the regulation mechanism, the DNMTs promoter methylation sequence were analyzed. Compared to the C group, although there was less methylation at two CpG sites of DNMT1 (p < 0.05) and higher methylation at two CpG sites of DNMT3a (p < 0.05), there were no significant differences in methylation of the detected DNMT1 and DNMT3a promoter regions. However, there were lower methylation levels at five CpG sites of DNMT3b, which decreased methylation of detected DNMT3b promoter region on M group (p < 0.05). In conclusion, alterations of methylation regulated by melatonin may mediate development of cumulus cells in lambs.

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This paper describes the performance of 12 axially restrained RC columns (four for each type of cross section, i.e., +-, T-and L-shaped cross section) under fire conditions that were recently finished in South China University of Technology. The main objective of the paper is to investigate the effect of axial restraint on RC columns during both expanding and contracting phases. The RC columns were all initially concentrically loaded and subjected to ISO834 standard fire on all sides. Axial restraints were imposed at the top of the columns to simulate the restraining effect of the rest of the whole frame. Different degrees of axial restraint were obtained by varying the length of the restraining beam. The boundary conditions of the columns were considered as fixed-fixed for all tests. It is found that restrained RC columns behave quite differently to isolated ones. No typical 'runaway' failure of isolated RC columns was observed in the fire test. Finally, the finite element software, SAFIR, is employed to conduct a numerical analysis of the tests.