Decay Forms Research Articles

Characterization of Anisotropic Salt Weathering through Nondestructive Techniques Mapping Using a GIS Environment.

Doctrinal texts on architectural heritage conservation emphasize the importance of fully understanding the structural and material characteristics and utilizing information systems. Photogrammetry allows for the generation of detailed, geo-referenced Digital Elevation Models of architectural elements at a low cost, while GIS software enables the addition of layers of material characteristic data to these models, creating different property maps that can be combined through map algebra. This paper presents the results of the mechanical characterization of materials and salt-related decay forms of the polygonal apse of the 13th-century monastery of Santa María de Bonaval (Guadalajara, Spain), which is primarily affected by salt crystallization. Rock strength is estimated using on-site nondestructive testing (ultrasound pulse velocity and Leeb hardness). They are mapped and combined through map algebra to derive a single mechanical soundness index (MSI) to determine whether the decay of the walls could be dependent on the orientation. The presented results show that salt decay in the building is anisotropic, with the south-facing side of the apse displaying an overall lower MSI than the others. The relative overheating of the south-facing side of the apse enhances the effect of salt crystallization, thereby promoting phase transitions between epsomite and hexahydrite.

Study on the Properties of FEVE Modified with Ag2O/OH-MWCNTS Nanocomposites for Use as Adhesives for Wooden Heritage Objects.

The durability of wooden heritage objects and sites can be affected by external environmental factors, leading to decay, cracking, and other forms of deterioration, which might ultimately result in significant and irreversible loss. In this study, a FEVE resin was modified with Ag2O/OH-MWCNTS (MA), denoted as MAF, where three concentrations were prepared using in situ precipitation, and the resulting composite adhesive was characterized by a high viscosity and effective bacteriostatic properties, demonstrating a better viscosity and thermal stability, as well as antibacterial properties, than pure FEVE resin. The results show that MAF adhesives present good thermal stability, as evidenced by a lower mass loss rate following treatment at 800 °C compared to the pure FEVE resin. At a consistent shear rate, the viscosity of MAF demonstrates a notable increase with the proportion of MA, which is better than that of FEVE. This suggests that the nano-Ag2O particles in MA act as physical crosslinking agents in FEVE, improving the viscosity of the composite adhesive MAF. The adhesion strength between MAF and wood exhibits a similar trend, with wooden samples showing higher shear strengths as the proportion of MA increases in comparison to FEVE. Simultaneously, the antibacterial effects of the MAF adhesive exceeded 1 mm for Trichoderma, Aspergillus niger, and white rot fungi. The antibacterial activity of the MAF adhesive exhibited a direct correlation with the concentration of Ag2O/OH-MWCNTS, with the most pronounced inhibitory effect observed on Trichoderma. The MAF adhesive demonstrates promising prospects as an adhesive for wooden heritage artifacts, offering a novel approach for the rapid, environmentally friendly, and efficient development of composite adhesives with superior adhesive properties.

ENHANCED ALGORITHMS TO EXTRACT DECAY FORMS OF CONCRETE INFRASTRUCTURES FROM UAV PHOTOGRAMMETRIC DATA

Abstract. Nowadays, inspection and maintenance of infrastructures is one of the most crucial issues to be faced. The structural performances should be constantly checked, considering that especially ageing stock and extreme weather events deteriorate the network infrastructure over time. However, economic reasons and the practical difficulty of carrying out a targeted inspection makes the detection a major challenge. In most of the western countries, a high percentage of infrastructures has reached and exceeded the nominal life, so the detection plays a fundamental role for their proper functioning. In this paper, experimental algorithms were tested to extract the decay forms on a portion of concrete pillar. These algorithms were applied on a metric digital image, obtained by photogrammetric output. The finally accuracy was calculated considering as ground truth the visual inspection performed by a concrete expert and the confusion matrices, the overall accuracy and the kappa-coefficient were evaluated. Then, a comparison with existing algorithms was made using the same methodology. The stacking of the original RGB image with two of the experimental algorithms could increase the accuracy up to 5%, while the common ones did not produced significant improvements. The final purpose of this work was to propose a semi-automatic/automatic procedure to detect concrete decay forms and, therefore, help the infrastructure management. The awareness is essential to provide the best practices to ensure safety and adequate performance over time.

Commensurate and incommensurate Haldane phases for a spin-1 bilinear–biquadratic model

Commensurate and incommensurate Haldane phases for a spin-1 bilinear-biquadratic model are investigated using an infinite matrix product state algorithm. The bipartite entanglement entropy can detect a transition point between the two phases. In both phases, the entanglement spectrum shows double degeneracy. We calculate the nonlocal order parameter of the bond-centered inversion in both phases, which rapidly approaches a saturation value of −1 as the segment length increases. The nonlocal order parameter of the bond-centered inversion with a saturation value −1 and the nonzero value string order indicate that the Haldane phase is a symmetry-protected topological phase. To distinguish the commensurate and incommensurate Haldane phases, the transversal spin correlation and corresponding momentum distribution of the structure factor are analyzed. As a result, the transversal spin correlations exhibit different decay forms in both phases.

Structural entropy and spatial decay of quasimodes in Vogel spirals

We investigate the spatial decay and temporal localization properties of quasimodes (i.e., scattering resonances) of two-dimensional Vogel spirals, composed of deterministic, aperiodic arrays of electric dipoles. By determining the structural entropy and localization maps of Vogel spirals using the Green's matrix method, we show that three distinctive decay types of quasimodes coexist in Vogel spirals: exponential, power-law, and Gaussian. While the exponential and the power-law decays typically occur in disordered media and multifractal systems, respectively, the Gaussian decay is demonstrated to characterize, on average, the most localized quasimodes of Vogel spirals, both spatially (smallest participation ratios) and temporarily (longest lifetimes). These decay forms are demonstrated by a no-fitting analysis of the localization maps, independently corroborated by calculating the electric field in real space, which also provides a direct evidence of the algebraic spatial decay of critical quasimodes. Altogether our findings unveil a rich spectrum of both long-lived and spatially localized quasimodes that coexist in Vogel spirals and can be of direct relevance to novel optical functionalities for applications to light sources and sensing devices.

UAV Photogrammetry for Concrete Bridge Inspection Using Object-Based Image Analysis (OBIA)

Monitoring infrastructures is becoming an important and challenging issue. In Italy, the heritage consists of more than 60,000 bridges, which need to be inspected and detected in order to guarantee their strength and durability function during nominal lifespan. In this paper, a non-destructive survey methodology for study concrete bridges surface deterioration and viaducts is presented. Terrestrial and unmanned aerial vehicle (UAV) photogrammetry has been used for visual inspection of a standard concrete overpass in L’Aquila (Italy). The obtained orthomosaic has been processed by means of Object-Based Image Analysis (OBIA) to identify and classify deteriorated areas and decay forms. The results show a satisfactory identification and survey of deteriorated areas. It has also been possible to quantify metric information, such as width and length of cracks and extension of weathered areas. This allows to perform easy and fast periodic inspections over time in order to evaluate the evolution of deterioration and plan urgency of preservation or maintenance measures.

Semi-commercial testing of regional yeasts selected from North Patagonia Argentina for the biocontrol of pear postharvest decays

The efficacy of two regional yeasts, Pichia membranifaciens NPCC 1250 and Vishniacozyma victoriae NPCC 1263, for controlling pear postharvest decay was evaluated at large scale (semi-commercial conditions) in two different packing houses. The human safety of the two yeast strains was initially assayed by assessing growth at body temperature, pseudohyphal growth, phospholipases production, and growth in simulated gastric juice. Subsequently, yeasts biomass was produced in a bioreactor (22 L) containing 18 L of culture medium based on sugarcane molasses plus urea. The produced biomass, with/without CaCl2 (2% w/v) addition, was used in biocontrol experiments carried out at semi-commercial scale on Beurre d'Anjou and Packham’s Triumph pears. Vishniacozyma victoriae NPCC 1263 plus CaCl2 showed high performance on controlling decay caused by Penicillium expansum and Botrytis cinerea. On Beurre d'Anjou cv, P. expansum and B. cinerea incidence was reduced by 70% and 100%, respectively, after 90 days of commercial storage. On Packham’s Triumph the incidence of the two decay forms was 63% after 150 days. The two antagonistic yeasts were able to establish and colonize the surface of the fruits, with an estimated increase in the population density of approximately three orders of magnitude during the postharvest period. This work is the first to evaluate and demonstrate the efficacy of local biocontrol experiments with regional yeasts under semi-commercial conditions.

Energy dissipation analysis of oil wells sucker rod string

Sucker rod pumping systems are well-known artificial lift methods, thereby improving the efficiency of oil production. However, the periodic movement performed by the string makes the system susceptible to mechanical failures, promoting operational shutdowns. This paper presents a new approach to the vibrational analysis of the sucker rod string through a study of energy decay. The damped wave equation representing the oscillatory motion of the sucker rod lift system was solved analytically, and the energy of the solution was characterized by analyzing its behavior in space and time. The results show that the energy has a dissipative nature, promoting the vibrational attenuation in three different exponential decay forms. The results allow to characterize the damping limits of each exponential decay type. The approach proposed in this paper, by energy decay analysis, can serve as base to the development of new methodologies capable to detect anomalies and optimum operational conditions in sucker rod pump system.

Non-Destructive Testing for Building Diagnostics and Monitoring: Experience Achieved with Case Studies

Building inspection on site, in other words in-situ examinations of buildings is a troublesome work that necessitates the use of non-destructive investigation (NDT) techniques. One of the main concerns of non-destructive testing studies is to improve in-situ use of NDT techniques for diagnostic and monitoring studies. The quantitative infrared thermography (QIRT) and ultrasonic pulse velocity (UPV) measurements have distinct importance in that regard. The joint use of QIRT and ultrasonic testing allows in-situ evaluation and monitoring of historical structures and contemporary ones in relation to moisture, thermal, materials and structural failures while the buildings themselves remain intact. For instances, those methods are useful for detection of visible and invisible cracks, thermal bridges and damp zones in building materials, components and functional systems as well as for soundness assessment of materials and thermal performance assessment of building components. In addition, those methods are promising for moisture content analyses in materials and monitoring the success of conservation treatments or interventions in structures. The in-situ NDT studies for diagnostic purposes should start with the mapping of decay forms and scanning of building surfaces with infrared images. Quantitative analyses are shaped for data acquisition on site and at laboratory from representative sound and problem areas in structures or laboratory samples. Laboratory analyses are needed to support in-situ examinations and to establish the reference data for better interpretation of in situ data. Advances in laboratory tests using IRT and ultrasonic testing are guiding for in-situ materials investigations based on measurable parameters. The knowledge and experience on QIRT and ultrasonic testing are promising for the innovative studies on today’s materials technologies, building science and conservation/maintenance practices. Such studies demand a multi-disciplinary approach that leads to bring together knowledge on materials science and building science.

Non-Destructive Testing for Building Diagnostics and Monitoring: Experience Achieved with Case Studies

Building inspection on site, in other wordsin-situexaminations of buildings is a troublesome work that necessitates the use of non-destructive investigation (NDT) techniques. One of the main concerns of non-destructive testing studies is to improvein-situuse of NDT techniques for diagnostic and monitoring studies. The quantitative infrared thermography (QIRT) and ultrasonic pulse velocity (UPV) measurements have distinct importance in that regard. The joint use of QIRT and ultrasonic testing allowsin-situevaluation and monitoring of historical structures and contemporary ones in relation to moisture, thermal, materials and structural failures while the buildings themselves remain intact. For instances, those methods are useful for detection of visible and invisible cracks, thermal bridges and damp zones in building materials, components and functional systems as well as for soundness assessment of materials and thermal performance assessment of building components. In addition, those methods are promising for moisture content analyses in materials and monitoring the success of conservation treatments or interventions in structures. Thein-situNDT studies for diagnostic purposes should start with the mapping of decay forms and scanning of building surfaces with infrared images. Quantitative analyses are shaped for data acquisition on site and at laboratory from representative sound and problem areas in structures or laboratory samples. Laboratory analyses are needed to supportin-situexaminations and to establish the reference data for better interpretation of in situ data. Advances in laboratory tests using IRT and ultrasonic testing are guiding forin-situmaterials investigations based on measurable parameters. The knowledge and experience on QIRT and ultrasonic testing are promising for the innovative studies on today’s materials technologies, building science and conservation/maintenance practices. Such studies demand a multi-disciplinary approach that leads to bring together knowledge on materials science and building science.

Scaling relation of earthquake seismic data

We study the spatio-temporal characteristics of earthquakes, and find that power laws and allometric growth laws are both statistically significant in the seismic dataset. For further analyzing the complexity of earthquake sequence, an approach of weighted earthquake networks modeling is presented with using the seismic and rock mass datasets. The rock masses covering the entire region are used to divide the region into a lot of small areas. It is shown that the distributions of connectivities and link weights both follow power law decay forms. The discovery of allometric growth laws is important for studying the dynamics of massive earthquakes. The suggested earthquake network is helpful to study the interactions between rock masses and expand a research prototype for modeling seismicity on complex networks.

Stratigraphy, petrophysical characterization and 3D geological modelling of the historical quarry of Nueva Tabarca island (western Mediterranean): Implications on heritage conservation

The historical quarry of the Nueva Tabarca fortress (Mediterranean Sea, SE of Spain) was developed in a complex sedimentary Miocene deposit. Five lithostratigraphic units have been defined, including different lithologies such as breccias and microconglomerates (Unit 1), massive and laminated lithoarenites (Units 1, 3 and 5), calcarenites and biocalcirudites (Units 2 and 4). A complete stratigraphic description of this sequence has been carried out, as well as the petrophysical characterization of the most significant lithologies including the analysis of rock durability as well as hydraulic and mechanical properties. Regarding durability, the softest rocks correspond to those from the Unit 4, whilst samples from Units 2 and 5 are the most durable. Three weathering patterns were observed during the artificial ageing test according to both the velocity and intensity of the sample decay. Each pattern is explained according to water-circulation possibility through the rock, its porous system, and the mechanical strength. Rock weathering in monuments of Nueva Tabarca is quantified and discussed according to the results found in the laboratory. Several decay forms are observed in the building stones (mainly differential erosion, alveolization, and rounding forms). Both 3D photogrammetric and 3D geological model of the historical quarry were elaborated in order to quantify the extracted volume of building stones, differentiating the specific quarried percentage of each lithology. Correlation between the results obtained in the volumetric analysis of the historical quarry and the building stones used in the monuments has been carried out. 3D models were also used for determining the remaining rock volume in the current outcrops. Finally, a set of recommendations for future conservation works of the architectural heritage are proposed after the current availability of the different rock varieties and their petrophysical behaviour.

Cellular level distributions of Scots pine heartwood and knot heartwood extractives revealed by Raman spectroscopy imaging

Wood extractives are biologically active secondary metabolites that help protect wood and wood products from decay and other forms of biological attack. Despite the influence of distribution on their ability to protect wood, very few studies have investigated the distributions of extractives on a cellular level. In this paper, the distributions of extractives were studied in Scots pine (Pinus sylvestris L.) heartwood (HW) and knot heartwood by confocal Raman spectroscopy imaging. Pinosylvins, the antifungal phenolic extractives of pine, were found to be present in the cell walls, middle lamella, and lumina of tracheids. Their distribution suggested the existence of two different mechanisms of deposition and revealed similarities to the distribution of lignin. The potential binding of pinosylvins to lignin and their relatively low concentration in HW cell walls could explain why Scots pine HW is, on average, only moderately resistant to decay. Resin acids, the most abundant group of extractives in pine, were detected only within the lumina of tracheids and ray cells, where they may contribute to the reduced permeability of HW. The extractives distributions presented here help us understand the properties of HW and provide a deeper understanding of the origins of natural durability, which is of value in the current efforts to develop more environmentally friendly means of wood protection.

Generalized Moment Analysis of Magnetic Field Correlations for Accumulations of Spherical and Cylindrical Magnetic Perturbers

In biological tissue, an accumulation of similarly shaped objects with a susceptibility difference to the surrounding tissue generates a local distortion of the external magnetic field in magnetic resonance imaging. It induces stochastic field fluctuations that characteristically influence proton spin diffusion in the vicinity of these magnetic perturbers. The magnetic field correlation that is associated with such local magnetic field inhomogeneities can be expressed in the form of a dynamic frequency autocorrelation function that is related to the time evolution of the measured magnetization. Here, an eigenfunction expansion for two simple magnetic perturber shapes, that of spheres and cylinders, is considered for restricted spin diffusion in a simple model geometry. Then, the concept of generalized moment analysis, an approximation technique that is applied in the study of (non-)reactive processes that involve Brownian motion, allows to provide analytical expressions for the correlation function for different exponential decay forms. Results for the biexponential decay for both spherical and cylindrical magnetized objects are derived and compared with the frequently used (less accurate) monoexponential decay forms. They are in asymptotic agreement with the numerically exact value of the correlation function for long and short times.

Laminar gypsum crust on lede stone: Microspatial characterization and laboratory acid weathering

Gypsum crusts are typical decay forms on limestone in polluted urban environments. Their origin and relation to the stone facies have been thoroughly investigated in the past three decades. Here, we present the combined use of novel techniques for a microspatial structural, chemical and mechanical characterization of a laminar black gypsum crust on a sandy limestone. These techniques include i.a. X-ray computed microtomography, X-ray Fluorescence micromapping, permeability mapping and the scratch test. They reveal the typical architecture of a laminar gypsum crust, with an outer opaque layer, a subsurface gypsum crystallization layer and a deeper cracked zone passing irregularly into the sound stone. Gypsum crystallization is mostly restricted to an irregular outer zone with an average thickness of 500µm, while cracks are found deeper within the rock. These cracks decrease the rock strength to more than 27.5mm below the surface. Because of their surface parallel orientation and thickness of >10–100µm, they create the potential for surface scaling. This is shown by a laboratory acid test where the crack network extensively developed due to further exposure to an SO2 environment. The use of novel techniques opens potential for the study of different decay forms and can be used for stone diagnosis with regards to conservation studies.

Experimental study on the salt weathering resistance of fired clay bricks consolidated by ethyl silicate

Fired clay elements are widely diffused in architectural heritage, for both structural and ornamental purposes, and are susceptible to severe decay forms, hence their conservation is a very urgent task, requiring appropriate consolidants to restore their cohesion and mechanical strength. As fired clay bricks and terracotta artefacts contain silicate fractions, allowing ethyl silicate (ES) to chemically bond to the substrate, ES is supposed to be suitable for their consolidation and indeed it is used in some conservation works on this kind of material. However, its behaviour and performance on fired clay elements has not been systematically evaluated in the scientific literature, mostly when durability is concerned. This aspect is particularly relevant as diverging data can be found in the literature about the impact of ES on substrate durability, to such an extent that it was found to either increase or hamper materials resistance to decay, depending on the specific case in exam. In this study, the behaviour towards salts crystallisation of fired clay bricks treated by ethyl silicate was investigated, specifically focussing on the role of the application procedure, an aspect which is usually left to the conservatorists’ skilfulness but which is however of paramount importance for the treatment outcome. In particular, ES was applied by five and ten brush strokes, to assess how the different amount of product absorbed and its different distribution inside the porous substrate influence the final resistance of bricks to salt weathering. As a matter of fact, salt crystallization is commonly considered one of the most frequent and severe decay mechanism affecting bricks on site. Despite both treatments providing significant increases in mechanical properties and a limited modification in samples microstructure, durability was found to be dependent on the treatment conditions. Particular attention should be devoted to the amount of product applied, as higher product absorption, despite generally leading to better efficacy, could cause higher microstructural modifications, possibly hampering materials durability.

Damage quantification of built stone on Dark Gate (Belgrade, Serbia): sample of damage index application for decay rate evaluation

The Dark Gate is the monument of culture, part of the cultural and historical complex of the Belgrade Fortress. It is constructed of limestone blocks that after 270 years of exposure to environmental conditions and different anthropogenic influences show wide ranges of decay forms. During 2007, detail registration of all built limestone microfacies and weathering forms was done using tools of monument mapping. A correlation scheme “intensity– damage category” was made according to the type, intensity, and distribution of damage forms. For quantification of decay rate of the Dark Gate, damage indices were calculated on the bases of mapping results. Calculated values of damage indices (>3) reflected differences between separate zones of the gate (south–north facades, east–west oriented parts of the gate). This approach allowed assessment and comparison of weathering rates according to the gate’s position and the exposure of the stone to environmental influences. The linear damage index showed that the moderate damage is the dominant category on the entire monument, while the progressive damage index implies to the need of urgent intervention. After 7 years, re-evaluation of these parameters was done. New data of weathering mapping and recalculated values of damage indices reflected significant acceleration in decay rate. By comparing weathering maps and values of damage indices from 2007 and 2014, the eastern part of the gate was separated as the zone of the monument that had suffered the heaviest damage. Differences among the values of damage indices showed that the position of the gate is one of the main causes of the present state of stone blocks built in the Dark Gate. They also showed that a carefully made damage category scheme is a key diagnostic tool in each restoration project.

Scale dependency in the functional form of the distance decay relationship

We examine a novel mathematical approach which posits that the decay of similarity in community composition with increasing distance (aka distance decay) can be modeled as the sum of individual species joint‐probability vs distance relationships. Our model, supported by analyses of these curves from three datasets (North American breeding birds, North American taiga plants, and tropical forest trees), suggest that when sampling grain is large enough to avoid absences due to stochastic sampling effects, and/or sampling extent is large enough to generate species turnover through the deterministic crossing of environmental and/or geographical range limits, species joint‐probability over increasing distance will generally exhibit exponential decay. However, at small scales where occurrence is driven more by stochastic sampling effects, species joint‐probability curves exhibit a power‐law decay form. Lacking a theoretical prediction of how individual species joint‐probability relationships combine to generate community distance decay, we also performed a meta‐analysis of 26 ecological and 4 human‐system datasets, using non‐linear regression to mean and quantile non‐linear regression at tau = 0.95 for linear, exponential, and power‐law decay forms. These analyses demonstrate that the functional form of community distance decay – as shown by comparison of AIC ranks – is largely determined by observational scale, with power law decay prevailing within domains where the species pool remains constant, while exponential decay prevails at larger scales over which the species pool varies, paralleling the patterns predicted in our mathematical approach.

A correlation of breast cancer and calcium levels in hair analyzed by X-ray fluorescence.

Time variations of elemental concentrations and their abnormalities due to breast cancer have been observed along single hair strands by X-ray fluorescence excited by synchrotron radiation. The renal-controlled elements Ca, Sr, S, K, Cl, Br and P have upper and lower levels associated with gating and closing of ion channels in the hair-making cells. The Ca lower level is normal. In cases of Ca deficiency, with a decrease from the normal, store-operated Ca channel gating occurs so as to keep the hair Ca at the normal, and paradoxically high Ca levels near or at the upper level are produced by PTH-operated channel gating of the cells. Chronic Ca deficiency shows a temporal pattern along the hair consisting of a long-term duration of the upper [Ca] level, 10-month long decay to the lower level and abrupt increase to the upper level. The observation for hair from breast-cancer patients also shows the upper Ca level for the time period well before detection, and suggests that cancer is always generated at the long-lasting [Ca] upper level and the hair [Ca] decreases gradually toward the lower level with the cancer growth. This decay of [Ca] is accompanied by those of [Sr] and [K]. Their different decay forms can be explained by parathyroid hormone related peptide (PTHrP) in serum secreted from the cancer having 150 times longer dwell time on the PTH receptors than that of PTH. Patient hair has a memory for the entire cancer process from the state before cancer generation, and the pattern can be distinguished from concentration variation due to the chronic Ca deficiency without cancer, leading to a criterion for cancer detection by the ratio of [Sr]/[Ca]. The hair analysis is useful for early detection of cancer.

An urban geomonumental route focusing on the petrological and decay features of traditional building stones used in Madrid, Spain

The stone traditionally used to build cities contributes to their personality and attests to the geological substrate on which they stand. While stone decay in the built heritage can be attributed to a number of causes, anthropic activity has a particularly significant impact. The geomonumental routes project is one of the initiatives proposed in recent years for urban routes that convey geological fundamentals by observing the rocks present in heritage structures. Its innovative approach addresses traditional stone properties, original quarrying sites and mechanisms of decay. Madrid’s Royal Palace is a fine example of the use of traditional building stone in the centre of the Iberian Peninsula. In the geomonumental route proposed, the building doubles as an in situ laboratory that affords an overview of the main petrological properties of the two traditional stones most commonly used in the city’s built heritage, the forms of decay they are subject and the factors underlying such alterations. This route constitutes a tool for showing the main petrological features and decay forms in traditional building stones found in urban heritage facades, with a special focus on anthropic impact, primarily air pollution and the use of conservation treatments that time has proven to be unsuitable.