Analytical diagnosis methodology to evaluate nitrate impact on historical building materials

Nitrate salts have become of greater importance in the decay of materials from historical buildings due to changes in the environment. This work presents an analytical diagnosis methodology to evaluate the impact of nitrate salts in mortars and bricks, combining noninvasive and microdestructive analytical techniques together with chemometric and thermodynamic data analyses. The impact of nitrate salts cannot be well ascertained if other soluble salts are not taken into account. Therefore, the principal results from this work relate to nitrate salts but some results for other kinds of salts are included. Data from Raman microprobe spectroscopy and micro X-ray fluorescence (μ-XRF) are used to characterise the original composition and a first approximation of the nature of the decay compounds, mainly nitrates. The soluble salts are extracted and the anions and cations are quantified by means of ion chromatography with conductimetric detection for anions/cations and inductively coupled plasma mass spectrometry (ICP/MS) for cations. The values obtained allow two different data treatments to be applied. First, chemometric analysis is carried out to search for correlations among anions and cations. Second, thermodynamic modelling with the RUNSALT program is performed to search for environmental conditions of soluble salt formation. All the results are finally used to diagnose the impact of nitrates.     

On sign-coherence of c-vectors

Given a finite dimensional algebra A over an algebraically closed field, we consider the c-vectors such as defined by Fu in [18] and we give a new proof of its sign-coherence. Moreover, we characterise the modules whose dimension vectors are c-vectors as bricks respecting a functorially finiteness condition.     

Effect of concentration, particle size and the presence of protective coatings in DRIFT spectra of building materials

This paper discusses the effect of particle size (from under 45 to 425 μm), sample concentration (5 and 50% dilution in KBr) and the presence/absence of anti-graffiti coatings on the quality of diffuse reflectance spectra, specifically the spectra for limestone, granite and brick. In limestone, sample dilution was found to affect spectral resolution significantly, whereas the increase in particle size leads to a slight decrease in signal intensity. The presence of anti-graffiti protection was the factor that disturbed spectral quality most visibly, except in very dilute (5%) samples with a very fine particle size (under 45 μm). In more heterogeneous materials such as brick and granite, particle size proved to have a greater impact than dilution, while the presence of protective treatment was again the parameter with the greatest effect on quality and consequently signal reproducibility. This effect was slighter in very dilute samples with a small particle size.     

Sources of uncertainties in OSL dating of archaeological mortars: The case study of the Roman amphitheatre “Palais-Gallien” in Bordeaux

Archaeological mortars are more convenient and much more representative for the chronology of buildings than brick or wood constructions that can be re-used from older buildings. Before dating unknown samples of mortars, further investigation of OSL from mortars is required and the most efficient methodology needs to be established. In this study we compared the ages obtained by OSL dating of quartz extracted from mortars of the Roman amphitheatre Palais-Gallien in Bordeaux with independent age information.Resetting of the OSL signal occurred during the preparation of mortar when grains of sand (quartz) were extracted and mixed with lime and water. The mortar was subsequently hidden from light by embedding within the structure which is the event to be dated.Various factors contribute to uncertainties in the age determination. The frequency of measured equivalent doses reveals a large scattering. Optical bleaching of certain grains can be partial due to the short duration of the exposure to light. We worked with the single grain technique in order to find and select the grains that were sufficiently exposed to daylight. To determine the average equivalent dose, we tried three different approaches: a calculation of an arithmetic mean and one following either the central age model or the 3-parameter minimum age model, the latter turned out to be the only relevant way to evaluate the experimental data. The proportion of grains included in the calculation of the average equivalent dose represents 2.7–4.7 % of the overall analysed grains. The results obtained for the three out of four samples are approaching the expected age, however, the minimum doses and the corresponding ages are significantly over-estimated in case of two samples.The studied material is very coarse, which causes heterogeneity of irradiation at the single grain scale, and contributes to a dispersion of equivalent doses. Different analytical methods (scanning electron microscopy with energy dispersive X-ray spectroscopy cartography, Beta-radiography imaging, inductively coupled plasma mass spectrometry) were employed to demonstrate the presence of this phenomenon.Despite the extremely large proportion of high equivalent doses in equivalent dose distributions, there is an apparent presence of well-bleached grains at the beginning of equivalent dose distributions. The study shows the potential of dating mortars by single grain OSL.     

Comparison of double-pulse and single-pulse laser-induced breakdown spectroscopy techniques in the analysis of powdered samples of silicate raw materials for the brick-and-tile industry

Single- and double-pulse laser-induced breakdown spectroscopy techniques applied to the analysis of pressed pellets of silicate raw materials were compared in terms of precision, sensitivity and limits of detection. Two Nd:YAG lasers (1064 and 532 mm) in an orthogonal configuration with a reheating arrangement have been employed. The main factors influencing system performance were optimized, i.e. laser pulse energies and interpulse separation. The behaviour of plasma temperature was studied over a period of time and calibration curves for Mg were constructed for both the single and double-pulse setup. When comparing the single- and double-pulse techniques, limits of detection of Si and Mg for the double-pulse technique were found to be 10 times lower.     

非热平衡Schwarzschild de Sitter黑洞的熵

从Schwarzschild de Sitter时空背景下的Klein Gordon方程出发，利用brick wall方法计算了黑洞的自由能和熵。这种黑洞由于存在两个视界面，而且它们的温度不相同，因此用一般方法计算熵存在着一定的困难。采用改进的brick wall模型，认为自由能和熵主要来自于视界附近薄层的贡献，很好地解决了这一困难，并得到了满意的结果。结果表明，这种黑洞的熵为它的两个视界面积之和的1/4，与人们预期的结果相符。由此可见，渐近de Sitter时空中的黑洞熵除了黑洞视界面的贡献之外，还应包括宇宙视界面的贡献。这从一定程度上揭示了黑洞熵与视界面积之间的内在联系，也更进一步地揭示了brick wall模型的本质。     

ICP-AES法测定砖茶中多种生命元素

建立了用ICP-AES法分析砖茶中Ca,Mg,K,Al,P,Cu,Zn,Fe,Mn等9种生命元素的方法,相对标准偏差在2.11%～8.68% 之间,标准物质的测定结果满意,方法简便可靠。对砖茶中9种元素分析结果与普通茶叶作了比较分析, 结果表明砖茶中P,Zn,K,Cu的含量均低于普通茶叶,分别只有普通茶叶的48.70%,78.19%,85.68%和98.78%,而Al,Fe,Mn,Ca,Mg的含量均高于普通茶叶,分别是普通茶叶的5.78,3.26,2.19,2.11和1.64倍。文章为研究砖茶中生命元素对饮茶型氟中毒的影响因素提供了大量有益的参考数据。     

Rapid radiochemical method for determination of actinides in emergency concrete and brick samples

A new rapid method for the determination of actinides in emergency concrete and brick samples has been developed at the Savannah River Site Environmental Lab (Aiken, SC, USA) that can be used in emergency response situations or for routine analysis. If a radiological dispersive device (RDD), Improvised Nuclear Device (IND) or nuclear accident occurs, there will be a urgent need for rapid analyses of many different environmental matrices, including building materials such as concrete and brick, to support dose mitigation and environmental clean-up. The new method for actinides in concrete and brick method utilizes a rapid sodium hydroxide fusion method, a lanthanum fluoride matrix removal step, and a column separation process with stacked TEVA, TRU and DGA Resin cartridges. Alpha emitters are prepared using rare earth microprecipitation for counting by alpha spectrometry. The method showed high chemical recoveries and effective removal of interferences. The determination of actinides in concrete and brick sample analysis can be performed in less than 8 h with excellent quality for emergency samples. The rapid fusion technique is a rugged sample digestion method that ensures that any refractory actinide particles are effectively digested.     

A |torus like黑洞熵与能斯特定理

利用 Brick wall 方法,计算非球坐标系,非渐近平直的 torus like 黑洞背景下标量场的自由能和熵. 结果表明，在非渐近平直时空,黑洞具有内外视界时， 所得熵不仅与外视界面积有关，而且也是内视界的函数.进一步证明，用内外视界参量表达的熵，在黑洞辐射温度趋于零时，黑洞的熵也趋于零，它满足能斯特定理，可视为黑洞的普朗克绝对熵.     

Analytical methods for the characterization of surface finishing in bricks

The recent restoration works of Santo Stefano Church Façade (XV century) in Venice have shown traces variously saved of different kind of surface finishes. These finishes were found on the brick's surface both in the masonry and in the decorative elements.Different brick's surface and decorative tile samples were investigated using several techniques: optical microscopy, scanning electron-microscopy, thermal analysis, infrared spectroscopy and reflectance Fourier transform infrared microspectroscopy.The evaluation of the reached results was used to understand the decorative techniques and to recognize the material employed.