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Cyanobacteria are widespread photosynthetic microorganisms among which some are able to fix atmospheric nitrogen. We investigated the impact of indigenous cyanobacteria strains (Nostoc) inoculation on physical characteristics of poorly aggregated soils from Guquka (Eastern Cape, South Africa). The soil aggregates (3-5 mm) were arranged into a layer of 10-20 mm thick, and sprayed with cyanobacteria solution. Subsequently the inoculated and un-inoculated samples were incubated (30°C, 80% humidity, continuous illumination at 100 lmol m -2 s -1 ). Their micromorphological characteristics and aggregate stability were investigated, after 1, 2, 3, 4 and 6 weeks of incubation, by using high resolution Cryo-SEM and aggregate breakdown tests.Micromorphological investigations revealed that the surface of uninoculated samples remained uncovered, while the inoculated samples were partially covered by cyanobacteria material after one week of incubation. A dense superficial network of cyanobacterial filaments and extracellular polymer secretions (EPS) covered their surface after 4 and 6 weeks of incubation. Organo-mineral aggregates comprising cyanobacterial filaments and EPS were observed after 6 weeks of incubation. The results of aggregate breakdown tests showed no significant difference between un-inoculated samples after 1, 2, 3, 4 or 6 weeks, while they revealed improvement of aggregate stability for inoculated samples. The improvement of aggregate stability appeared in a short while following inoculation and increased gradually with time and cyanobacteria growth. The increase in aggregate stability is likely related to the changes induced in micromorphological characteristics by cyanobacterial filaments and EPS. It reflects the effect of coating, enmeshment, binding and gluing of aggregates and isolated mineral particles by cyanobacteria material.

Linqing brick is very famous in Chinese history. In 2008, "The manufacturing process of Linqing brick" was selected as the intangible cultural heritage list in China. Now in China, how to identify the origin of Linqing brick is an important issue in archeology and architectural history research. It can be used to verify some assumptions about the history of heritage buildings which cannot be solved only by historical documents. It can also be used to study the history of Linqing brick. Field portable X-ray fluorescence spectrometry (FPXRF) can quickly and non-destructively determine the main elements and concentrations of Linqing brick in situ. It may be significant for identifying the origin of Linqing brick. But FPXRF could be affected by many factors and it can only measure the element concentrations of surface. Which method we use can provide the most reliable data is an important issue. The aim of this study was to verify the reliability of FPXRF and to systematically evaluate different influential factors on measurement precision and accuracy, which can help with scientific advice for its use. We set up four experiments to determine the influential factors and assess reliability by cross validation using ICP-OES. Finally, we ensured that the FPXRF was reliable and determined the scientific advice required to use it to measure the main elements and concentrations of Linqing brick.

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