Safety evaluation of the temporary consolidant based on a zebrafish embryo model.

Temporary consolidants, such as cyclododecane, menthol, coumarin, and ethyl maltol, are proved to be effective for urgent conservation in archaeological field. However, the safety of these temporary consolidants is still unknown although they are always heavily used in archaeological field. Thus reports on the toxicity of these temporary consolidants are limited. Here, a zebrafish model was used for safety evaluation of these four temporary consolidants. In the present study, four temporary consolidants, including cyclododecane, menthol, coumarin, and ethyl maltol, at different concentrations were incubated with zebrafish embryos, and their biological toxic effects were firstly evaluated. It was shown that embryo exposure to temporary consolidants resulted in an increased mortality and malformation rate, and a decreased hatching rate. The order of embryo toxicity of the four types of temporary consolidants tested was menthol > coumarin > ethyl maltol > cyclododecane. Although the embryo toxicity of cyclododecane was minimal, some studies have indicated that this temporary consolidant could be bioaccumulated. The results also suggested that the zebrafish embryos can serve as a reliable model for the evaluation of embryo toxicity of temporary consolidants, as this model could offer the possibility to perform the rapid, medium throughput, cost-effective analyses.

[The Analysis of Traditional Lime Mortars from Zhejiang Province, China].

The components of ancient mortars have always been an important research field in historic building conservation. It has been well known that using traditional mortars in conservation projects have many advantages, such as compatibility and stability. So, developing new binding materials based on traditional mortar has become an international study hotspot. With China's economic development, the protection of ancient buildings also began to put on the agenda, but the understanding on Chinese traditional mortar is limited, and rare literatures are reported. In the present work, the authors investigate seven ancient city wall sites in Zhejiang Province in situ, and subsequently laboratory analysis were carried out on collected mortar samples. The characterizations of mortar samples were made by multi-density gauge, XRD, FTIR, TG-DSC and wet chemical analysis. The experimental results showed that: the main component of masonry mortars is calcium carbonate, the content between 75% - 90%, and they should be made from relatively pure lime mortar. The raw materials of mortar samples were mainly calcareous quick lime, and sample from Taizhou city also contained magnesium quick lime. There are four city walls were built by sticky-rice mortars. It suggests that the technology of adding the sticky rice soup into mortar was universal in the Ming Dynasties. These mortars have lower density between 1.2 and 1.9 g x cm(-3); this outcome should be the result of long-term natural erosion. We have also analyzed other chemical and physical characteristics of these masonry mortars. The results can afford the basic data for the future repairmen programs, development of new protective materials, and comparative study of mortars.

[Study on Archaeological Lime Powders from Taosi and Yinxu Sites by FTIR].

Archaeological lime powders samples from Taosi and Yinxu sites, natural limestone and experimentally prepared lime mortar were investigated by means of Fourier transform infrared spectrometry (FTIR) to identify the raw material of lime powders from Taosi and Yinxu sites. Results show that ν2/ν4 ratio of calcite resulted from carbonation reaction of man-made lime is around 6.31, which is higher than that of calcite in natural limestone and reflects the difference in the disorder of calcite crystal structure among the natural limestone and prepared lime mortar. With additional grinding, the values of v2 and ν4 in natural limestone and prepared lime mortar decrease. Meanwhile, the trend lines of ν2 versus ν4 for calcite in experimentally prepared lime mortar have a steeper slope when compared to calcite in natural limestone. These imply that ν2/ν4 ratio and the slope of the trend lines of ν2 versus ν4 can be used to determine the archaeological man-made lime. Based on the experiment results, it is possible that the archaeological lime powder from Taosi and Yinxu sites was prepared using man-made lime and the ancient Chinese have mastered the calcining technology of man-made lime in the late Neolithic period about 4 300 years ago.

[Study on the traditional lime mortar from the memorial archway in the southern Anhui province].

The traditional lime mortar was investigated by means of scanning electron microscope (SEM), X-ray diffractometry and Fourier transform infrared spectrometry (FTIR). The results show that the mortar from the memorial archway in the southern Anhui province was the organic-inorganic composite materials composed of lime with tung oil or sticky rice. It was found that the excellent performance of the tung oil-lime mortar can be explained by the compact lamellar organic-inorganic composite structure that was produced by carbonization reaction of lime, cross-linking reactions of tung oil and oxygen and complexing reaction of Ca2+ and -COO-. The compact micro-structure of sticky rice-lime mortar, which was produced due to carbonation process of lime controlled by amylopectin, should be the cause of the good performance of this kind of organic-inorganic mortar.

[Study on the mechanism of liesegang pattern development during carbonating of traditional sticky rice-lime mortar].

Liesegang patterns in traditional sticky rice-lime mortar undergoing carbonation were investigated by means of FTIR, XRD and SEM. Results indicate that well-developed Liesegang patterns only occur in the mortar prepared with aged lime and sticky rice. The smaller Ca(OH)2 particle size in aged lime and the control of the sticky rice for the crystallization of calcium carbonate lead to the small pores in this mortar. These small pores can make Ca2+ and CO3(2-) highly supersaturated, which explains the reason why Liesegang pattern developed in the sticky rice-aged lime mortar. The formed metastable aragonite proves that Liesegang pattern could be explained based on the post-nucleation theory.