Synchrotron radiation μ X-ray diffraction in transmission geometry for investigating the penetration depth of conservation treatments on cultural heritage stone materials

The assessment of the penetration depth of conservation treatments applied to cultural heritage stone materials is a burning issue in conservation science. Several analytical approaches have been proposed but, at present, many of them are not fully exhaustive to define in a direct way the composition and location of the conservation products formed after inorganic mineral treatments. Here, we explored, for the first time, the analytical capability of synchrotron radiation m X-ray diffraction in transmission geometry (SR-mTXRD) for the study of the crystal chemistry and penetration depth of the consolidating phases formed after the application of diammonium hydrogen phosphate (DAP) treatments on a porous carbonatic stone (Noto limestone). The SR-mTXRD approach provided unambiguous information on the nature of the newly formed calcium phosphates (hydroxyapatite, HAP, and octacalcium phosphate, OCP) with depth, supplying important indications of the diffusion mechanism and the reactivity of the substrate. Qualitative and semi-quantitative data were obtained at the microscale with a non-destructive protocol and an outstanding signal-to-noise ratio. The SR-mTXRD approach opens a new analytical scenario for the investigation of a wide range of cultural heritage materials, including natural and artificial stone materials, painted stratigraphies, metals, glasses and their decay products. Furthermore, it can potentially be used to characterize the penetration depth of a phase \u201cA\u201d (or more crystalline phases) in a matrix \u201cB\u201d also beyond the cultural heritage field, demonstrating the potential wide impact of the study

Scientific investigation to look into the conservation history of a Tang Dynasty terracotta Dancing Horse

AbstractA terracotta Dancing Horse sculpture dating to the Tang Dynasty (China) and owned by the Cincinnati Art Museum (US) is the topic of the present investigation. Besides its intrinsic artistic and historical values, the peculiarity of this horse concerns its conservation history; it shows extensive breakage signs and restoration and above all, the presence of an odd tassel on the frontal part of the head. Nine tassels are present on the two sides of the body, which is very common for these kinds of sculptures. Here, a scientific survey of this masterpiece is proposed aimed at looking into its conservation history, shedding light into the condition of the body and the tassels and the presence of residual conservation products applied during its troubled history. A comparative molecular, chemical and mineralogical study of the tassels is carried out focused on the identification of original and non-original materials, eventually added during restoration works. The multi-analytical protocol has been optimized for achieving as much information as possible from the available samples, a few mg of powders. X-ray powder diffraction and Raman Spectroscopy techniques have been followed by Fourier Transformed Infrared Spectroscopy and Ionic Chromatography, using the same small aliquot of powders. Scientific investigations highlighted that the odd tassel on the head and other two tassels on the body are not original, but replaced or added in subsequent time. Their composition includes both organic (polyester resin and/or phthalate) and inorganic compounds (sulphates and carbonates). Further data on original terracotta composition, decay substances and applied conservation products, provided new knowledge on past restoration treatments and cultural value. Importantly, the outcomes achieved with X-ray powder diffraction to identify the tassels authenticity were matched by Raman Spectroscopy, a technique that can be also used in situ with portable instruments, paving the way to non-invasive in situ authenticity studies as future perspective

Grazing incidence synchrotron X-ray diffraction of marbles consolidated with diammonium hydrogen phosphate treatments : non-destructive probing of buried minerals

Diammonium hydrogen phosphate (DAP)-based consolidating treatments react with carbonatic stones and form calcium phosphates phases, whose composition depends on the availability of free calcium ions. In this work, an innovative non-destructive approach based on grazing incidence X-ray diffraction (GIXRD) with synchrotron radiation (SR) is used to investigate DAP-treated Carrara marble specimens and to study the influence of the substrate composition on the crystallization of calcium phosphate phases. The outcomes indicate that the presence of compositional micro-heterogeneity of Carrara marble favours the formation of specific phases. Dicalcium phosphate dihydrate, a calcium phosphate with a low Ca/P molar ratio, is formed on carbonatic phases with a low Ca amount, such as dolomite grains and Mg-containing veins. Furthermore, this study highlights the potentialities of SR-GIXRD as a powerful non-destructive tool for the diagnostic of Cultural Heritage objects since it allows investigating the conservation history of stone materials and their interaction with the environment

Diammonium Hydrogenphosphate Treatment on Dolostone : the Role of Mg in the Crystallization Process

The diammonium hydrogenphosphate (DAP, (NH4)2HPO4) reaction with calcite has been extensively investigated. The availability of free calcium ions in the reaction environment has been acknowledged as a crucial factor in the crystallization of calcium phosphates with a high (hydroxyapatite, Ca/P 1.67) or low Ca/P molar ratio (dicalcium phosphate dihydrate, Ca/P 1.00; octacalcium phosphate, Ca/P 1.33). On the contrary, no data are available on the DAP interaction at room temperature with dolomite in terms of reaction mechanism and composition of the reaction products. Here, a multi-analytical approach based on scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectrometry (EDS) and X-ray powder diffraction before and after heating treatments is proposed to explore how the formation of calcium phosphates occur on Mg-enriched substrates and if the presence of magnesium ions during the reaction influences the crystallization process of calcium phosphates. The DAP reaction with polycrystalline dolomite gives rise to the formation of struvite and of poorly crystalline hydroxyapatite. Calcium and magnesium ions mutually interfered in the crystallization of magnesium and calcium phosphates, respectively, whose effects influenced the properties (size, micro-morphology, composition and crystallinity) of the newly-formed phases

Synthesis of calcium oxalate trihydrate: new data by vibrational spectroscopy and synchrotron X-ray diffraction

Calcium oxalate is found in nature in three different crystalline states determined by the number of H2O in the unit formula (whewellite CaC2O4\ub7H2O, COM; weddellite CaC2O4\ub7(2 + x)H2O, COD and caoxite CaC2O4\ub73H2O, COT). The properties of these materials are relevant in the field of biomedicine, cultural heritage and mineralogy. In two previous papers, we have used X-ray diffraction and vibrational spectroscopy (infrared and Raman) to derive information on crystal and molecular structures of COM and COD. In this paper, we complete the synthesis and analysis on the third form, COT, and present a comparative study of the data collected from the three crystalline states. The experiments clearly highlight the role played by the H2O molecules linked within the structure by different kinds of hydrogen bonds. The vibrational assignment of the infrared and Raman bands are critically proposed. The fact relevant for the work in biomedicine, cultural heritage and crystallography is that a simple examination of the spectra allows quickly to determine the chemical nature of the material in an unknown sample even in a minute quantity or in awkward experimental conditions

Cross-Cultural Differences in the Perception of Lamb between New Zealand and Chinese Consumers in New Zealand

This study investigated differences between general New Zealand consumers and ethnic Chinese consumers living in New Zealand regarding the importance of lamb attributes at the point of purchase and opinions of New Zealand lamb. A central location test survey was undertaken with 156 New Zealand consumers living in Dunedin, New Zealand, and 159 Chinese consumers living in Auckland, New Zealand. In terms of importance at the point of purchase, Chinese consumers rated a number of attributes as more important than New Zealand consumers by a difference of >1.0 on a 9-point Likert scale for importance: animal origin, feeding, age, presence of hormones/residues, traceability, food safety, place of purchase, brand/quality label, and label information (p 1.0 on a 7-point Likert scale for agreement. New Zealand consumers considered New Zealand lamb more traditional and boring (p < 0.05); however, the differences in scores were <1.0.info:eu-repo/semantics/publishedVersio

Calcium phosphates crystallized on Carrara marble after phosphate-based consolidating treatment

Diammonium hydrogen phosphate (DAP, (NH4)2HPO4) solutions have been introduced in the conservation field as a new inorganic-mineral treatments to consolidate or protect decayed carbonatic stone materials of historical monuments [1]. The treatment forms calcium phosphates through a dissolution and re-crystallization reaction, which takes place between hydrogen phosphate groups of the reagent and calcium ions of calcite of the substrate. Calcium phosphates nucleate on calcite grains with a pseudomorphic replacement reaction, and form a crystal network able to restore the lost cohesion of the microstructure. Despite the high number of studies on the crystallization of calcium phosphates and their formation on the surface of carbonatic substrates, only a few studies explored the formation of calcium phosphate phases on marbles treated with DAP and using calcite of the substrate as unique source for calcium ions [2-4]. Previous studies revealed a non-stoichiometric reaction that lead to the formation of a mixture of phases, each one characterized by different Ca/P molar ratio, solubility and stability [4]. In this study, we carry out a non-destructive synchrotron radiation grazing incidence X-ray diffraction (SR-GIXRD) investigation on DAP-treated marbles to determine how the mineralogical composition of the stone substrate affects the crystallization of stable and metastable calcium phosphates. The analyses were performed on Carrara marble specimens treated by capillarity by 0.76 M DAP solutions. Our results indicate that the presence of compositional micro-heterogeneity of Carrara marble favours the formation of specific phases. In general, the composition and the localization of the phases directly depend on the availability of free Ca2+ ions. Dicalcium phosphate dihydrate, a calcium phosphate with a low Ca/P molar ratio, is formed on carbonatic phases with a low Ca content, such as dolomite grains and Mg-containing veins. Octacalcium phosphate (OCP, Ca8(HPO4)2\ub75H2O) and poorly-crystalline partially-substituted hydroxyapatite (HAP, Ca5(PO4)3OH) are the foremost newly-formed phases when the substrate is mainly composed by calcite. This study shed light on the potentialities of SR-GIXRD as a powerful non-destructive tool for the diagnostic of Cultural Heritage objects, since it allows investigating the conservation history of stone materials with an in depth evaluation of DAP consolidating processes [5]. [1] M. Matteini, S. Rescic, F. Fratini, G. Botticelli Int. J. Archit. Herit. Conserv. Anal. Restor. 2011, 5, 717. [2] M. Kamiya, J. Hatta, E. Shimada, Y. Ikuma, M. Yoshimura, H. Monma Mater. Sci. Eng. B 2004, 111, 226. [3] S. Naidu and G. W. Scherer J. Colloid Interface Sci. 2014, 435, 128. [4] E. Possenti, C. Colombo, D. Bersani, M. Bertasa, A. Botteon, C. Conti, P. P. Lottici, M. Realini Microchem. J. 2016, 127, 79. [5] E. Possenti, C. Colombo, C. Conti, L. Gigli, M. Merlini, J. R. Plaisier, M. Realini, G. D. Gatta Appl. Phys. A 2018, 124, 383

Studio della quota di volo mediante GNSS, altimetro radar e barometro per rilievi di spettroscopia gamma da velivolo

Lo studio della distribuzione dei radionuclidi terrestri (238U, 232Th e 40K) realizzato mediante tecniche di spettroscopia gamma da velivolo è influenzato dalla quota a cui il rivelatore si trova rispetto al suolo. Un'incertezza del 10% a 100 m di altezza origina un errore nella stima del segnale gamma del 208Tl, appartenente alla catena di decadimenti del 232Th, dell’ordine del 7%. L'impiego di una nuova classe di spettrometri montati a bordo di UAV (Unmanned Aerial Vehicle) per raffinate misure in contesti ostili o remoti rende necessaria un'accurata stima in real time della quota di volo. Il Radgyro è un velivolo dedicato a survey multiparametrici, capace di trasportare strumentazione pari ad un payload massimo di 120 kg, tra cui quattro spettrometri gamma NaI(Tl). Una stazione inerziale con ricevitore integrato GNSS (Global Navigation Satellite System) restituisce l'assetto del velivolo con una frequenza massima di 400 Hz. Il velivolo è dotato di un network di tre ricevitori GNSS posizionati alle estremità della carena del velivolo. Un altimetro radar a 24 GHz rileva la quota con una frequenza di 60 Hz. La misura di pressione e temperatura consente di ricavare la quota barometrica a 2 Hz. Con l'obiettivo di studiare le incertezze associate alle misure della quota di volo acquisite dagli altimetri in relazione ai dati GNSS, sono stati realizzati tre voli sul mare in un range di altezze comprese tra 31 m e 249 m, per un totale di 4702 secondi di volo effettivo. Al termine dello studio è possibile concludere che l'errore complessivo delle abbondanze di K, U e Th aumenta di 7.7%, 0.5% e 2.7% rispettivamente, a causa delle incertezze della quota di volo

The Implications of COVID-19 on Chinese Consumer Preferences for Lamb Meat

This study assessed if Chinese consumer attitudes towards a range of lamb attributes (such as origin, food safety, appearance, taste, price), and their opinions of New Zealand lamb (9- and 7-point Likert scales, respectively), had changed since the outbreak COVID-19. The same survey was carried out in Shanghai and Beijing pre (December 2018) and post COVID-19 (November 2020), ~9 months after China’s initial outbreak, with 500 and 523 consumers, respectively. From December 2018 to November 2020, there was an increase in the proportion of Chinese consumers purchasing red meat online or from a butcher, and cooking their lamb well-done. In contrast, there were minimal differences in Chinese consumer ratings between December 2018 and November 2020 for different lamb attributes and opinions of New Zealand lamb. Cluster analysis revealed that many consumers (140 in December 2018/376 in November 2020) used only a small portion of the high end of the scale when rating lamb attributes, resulting in little differences between the attributes. This study suggests COVID-19 has enhanced some food safety related behaviors but had little effect on Chinese opinions and preferences for New Zealand lamb attributes. It also highlights that survey design should be carefully considered when collecting responses from Chinese consumers.info:eu-repo/semantics/publishedVersio

Comparison between RGB and RGB-D cameras for supporting low-cost GNSS urban navigation

A pure GNSS navigation is often unreliable in urban areas because of the presence of obstructions, thus preventing a correct reception of the satellite signal. The bridging between GNSS outages, as well as the vehicle attitude reconstruction, can be recovered by using complementary information, such as visual data acquired by RGB-D or RGB cameras. In this work, the possibility of integrating low-cost GNSS and visual data by means of an extended Kalman filter has been investigated. The focus is on the comparison between the use of RGB-D or RGB cameras. In particular, a Microsoft Kinect device (second generation) and a mirrorless Canon EOS M RGB camera have been compared. The former is an interesting RGB-D camera because of its low-cost, easiness of use and raw data accessibility. The latter has been selected for the high-quality of the acquired images and for the possibility of mounting fixed focal length lenses with a lower weight and cost with respect to a reflex camera. The designed extended Kalman filter takes as input the GNSS-only trajectory and the relative orientation between subsequent pairs of images. Depending on the visual data acquisition system, the filter is different because RGB-D cameras acquire both RGB and depth data, allowing to solve the scale problem, which is instead typical of image-only solutions. The two systems and filtering approaches were assessed by ad-hoc experimental tests, showing that the use of a Kinect device for supporting a u-blox low-cost receiver led to a trajectory with a decimeter accuracy, that is 15% better than the one obtained when using the Canon EOS M camera