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Article

Green Biocidal Nanotechnology Use for Urban Stone-Built Heritage—Case Study from Oradea, Romania

by
Dorina Camelia Ilies
1,
Lucian Blaga
1,
Alexandru Ilies
1,
Ana Cornelia Pereș
2,
Tudor Caciora
1,*,
Thowayeb H. Hassan
3,4,
Nicolaie Hodor
5,
Alexandru Turza
6,
Hamid R. Taghiyari
7,
Lucian Barbu-Tudoran
6,8,
Ranjan Kumar Dahal
9,
Paula Dejeu
10,
Bahodirhon Safarov
11 and
Mallik Akram Hossain
12
1
Department of Geography, Tourism and Territorial Planning, Faculty of Geography, Tourism and Sport, University of Oradea, 1 Universitatii Street, 410087 Oradea, Romania
2
Department of Environmental Engineering, Faculty of Environmental Protection, University of Oradea, Magheru Street 26, 410087 Oradea, Romania
3
Department of Social Studies, College of Arts, King Faisal University, Al Ahsa 31982, Saudi Arabia
4
Tourism Studies Department, Faculty of Tourism and Hotel Management, Helwan University, Cairo 12612, Egypt
5
Faculty of Geography, “Babes-Bolyai” University, 5-6 Clinicilor Street, 400006 Cluj-Napoca, Romania
6
National Institute for R&D of Isotopic and Molecular Technologies, 67-103 Donat Street, 400293 Cluj-Napoca, Romania
7
Faculty of Materials Engineering & New Technologies, Shahid Rajaee Teacher Training University, Tehran 16788-15811, Iran
8
Electron Microscopy Center “Prof. C. Craciun”, Faculty of Biology & Geology, “Babes-Bolyai” University, 5-7 Clinicilor Str., 400006 Cluj-Napoca, Romania
9
Central Department of Geology, Tribhuvan University Kirtipur, Kathmandu 44618, Nepal
10
Medical Laboratory Service M.D., Bethany Medical Clinic Oradea, Bihor County, 410004 Oradea, Romania
11
Department of Digital Economy, Samarkand State University, Samarkand 140105, Uzbekistan
12
Department of Geography and Environment, Jagannath University, Dhaka 1100, Bangladesh
 
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*
Author to whom correspondence should be addressed.
Minerals 2023, 13(9), 1170; https://doi.org/10.3390/min13091170
Submission received: 18 July 2023 / Revised: 28 August 2023 / Accepted: 31 August 2023 / Published: 4 September 2023
(This article belongs to the Special Issue Natural and Artificial Building Stones: Insights from Petrophysical Properties and Consolidation Procedures)
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Abstract

:
Heritage buildings clad with natural rock endure over time destruction caused by weathering mechanisms, pollution from urban areas, biodeterioration due to organisms, microorganisms, and also the anthropic factor. On the surface of the limestone samples taken from the ornamental natural rock with which the outside of Markovits-Mathéser house, Oradea, Romania, is clad, two species of fungi were inoculated in the laboratory: Aspergillus spp. and Cladosporium spp. Wollastonite was then applied, and from the imaging analysis (SEM), the inhibition of fungi by it is clearly observed (48 h after its application), which was also confirmed using the image segmentation method. It was also noted that the hydrophilicity of the aqueous suspension of wollastonite resulted in the absorption of water in the substrate, which in turn resulted in the drying out and surface breakage of the specimens. X-ray diffraction analysis showed the presence of the two phases (calcite and quartz) as in the starting sample, and also an additional phase assigned to wollastonite in the later phase of the experiment. An amorphous component, due to the applied gel composition, was also reported. This research highlights the fact that there are good premises for aqueous suspension of wollastonite to have a biocidal character for Aspegillus spp. and Cladosporium spp., when applied on natural stone used in the construction of heritage buildings located in temperate climates; due to its easy application, green and ecofriendly properties, and also low cost of acquisition and application.

1. Introduction

Tangible and intangible cultural heritage is a sustainable resource for the whole world. The responsible management of this type of heritage may have a positive effect in solving problems aimed at social inclusion and cohesion, improving the quality of the living environment, and in the industry of tourism [1,2].
Historical buildings and their heritage elements, monuments, and architectural complexes that are part of the tangible cultural heritage, are mostly built of natural rocks, and consequently suffer damage caused by weathering mechanisms [3,4,5,6]. Although initially the weathering process was conceived as an association of anical and chemical processes, research performed in recent decades has emphasised the ability of bacteria, fungi, plants, and other living organisms to intervene directly and alone (bioweathering or biodeterioration), or indirectly and in association with other forces in these mechanisms [7]. Their rhythm and intensity depend mainly on the physical and chemical properties of the rocks that make up heritage buildings and on the outdoor climatic conditions of the heritage site. In addition, climatic changes can intervene in accelerating their pace and intensity, the effect consisting of an increase in the rates of decay for buildings [8,9,10]. According to the IPCC [11], in Eastern Europe, an increase in periods with extremely high temperatures and heavy precipitation has been observed since 1950, and the studies carried out for Romania [12,13] indicate, since 1961, an increase in average temperatures (summer and spring), associated with an increase in extreme temperatures. Moreover, the way in which climate change manifests itself in urban climates, in which more than 70% of the cultural heritage properties inscribed on the World Heritage List are located [14], is different from that in rural climates [15]. Thus, urban climate is characterised by higher air temperature values compared to the countryside by up to 10 °C (in the case of large cities, and especially at night, in anticyclonic mode), and changes in the local atmospheric circulation can increase urban cloud cover and precipitation, with an impact on the increase in humidity over certain time intervals [16,17]. The statistical analyses performed by Liu et al. [18] on satellite data for land surface temperatures (2002–2021) show that the mean surface warming trend in the central part of the more than 2000 urban agglomerations worldwide is 29% higher than in the surrounding countryside. These climatic specificities, also present in Central–Eastern Europe, make mechanical weathering processes, such as thermoclastic (heating and cooling), wetting and drying, associated with chemical ones (solution, hydration, oxidation and reduction, carbonation) and biotics act with increased efficiency, and thus, represent a real danger to the built cultural heritage.
In these conditions, the cultural heritage loses buildings and architectural assemblies containing natural stone year after year due to decay and biodegradation. Artifacts exhibited or stored in inappropriate conditions in museums or private collections are affected by superficial or deep biodegradation processes, due to the impact of the cumulative action of thermohygrometric factors, pollutants, light, etc. [19,20,21,22]. In the case of natural rocks used in built cultural heritage monuments, biodegradation is due to organisms that act in isolation or in colonies, affecting the natural rock’s composition, even if it is a poor source of nutrients, and supports large differences in humidity, being affected by the mechanical erosion of wind, precipitation, or UV radiation [23], depending on the type of climate. An essential role in the alteration of the rock part of monuments and buildings is played by fungi, the epiphytic type that colonises and develops on the surface, and endolithic microorganisms by penetrating the rocks via intercrystallite spaces through active erosive chemical–mechanical processes [24,25,26]. When interpreting colonisation, biodegradation of built structures, interrelations between microorganisms, geological processes, and stone, geomicrobiology brings an important contribution and can provide information about remedies, and preventive or restorative treatments [25]. In the interaction of physical–chemical–mechanical processes and rock, damage to rock caused by microorganisms (fungi) consists in the penetration of rock by hyphae, which can lead to mechanical abrasions, fractures, and dislocations, resulting in chemically identical fragments with the original lithic support. The biocorrosive activity is carried out by the action of organic acids resulting from excretion processes, or due to oxidation processes of mineral-forming cations [19,27,28,29]. Aesthetic changes to the rock surface occur due to the synthesis and excretion of extracellular pigments of microcolonial fungi, highlighting colourations due to melanin in the mycelium and conidia, discolourations, dark stains (in the case of dematiaceous fungi), biogenic patina, black staining, black/grey spots, and biopitting phenomena on limestone and marble artworks [24,26,30,31]. The biogeochemical cycles that can take place, due to metabolic products (metabolic acids, sometimes very aggressive) of organisms, resulting from assimilation or lack of assimilation processes, can generate changes in the support rock in terms of minerals, with consequences for the degradation of minerals and rocks (biocorrosion—dissolution of the mineral substrate) or with the formation of secondary minerals (mycogenic minerals), activities, and processes based on the assimilation of mineral nutrient constituents and the metabolites of some anthropogenic pollutants [18,32,33,34]. Degradation of the natural stone from monuments and heritage buildings occurs under the effect of atmospheric pollution, humidity and its variation, temperature, freeze–thaw processes, air impurities (dust, smoke, etc.), soluble efflorescence, poorly soluble or insoluble salts whose action leads to physical erosion, chemical corrosion, and biological pollution and implicitly leads to diminishing the internal resistance of stone due to some harmful materials applied during previous restoration interventions [35,36]. Antibacterial agents for the protection and preservation of cultural heritage in natural stone do not fully succeed in annihilating the action of fungi resistant to chemical substances due to their thick and melanised cell walls [37]. Thus, lately, nanotechnology has taken off. It is a green technology and an efficient means to ensure sustainable development due to its ability to control air pollutants [38,39] and nanomaterials; in the case of the latter, conventional ones that are based on polymers [1]. Nanoscience promotes the engineering of nanomaterials that are compatible with the support material to preserve and protect the original characteristics, e.g., aesthetic, physical, chemical, mechanical; creating and maintaining a self-cleaning system, having thermal and biochemical stability, not being toxic, and with a low impact on the environment, having affordable prices, and good adaptability to different environments [20,22,40].
In this context, the current study aims to test the biocidal and antistatic nature of an aqueous suspension of wollastonite, in order to better preserve the natural stone used in the construction of buildings belonging to the cultural heritage. The rock was, thus, collected from the facade of a house built in the Art Nouveau style, in 1911, in the Municipality of Oradea, Romania.

2. Literature Review

Unwanted microorganisms on heritage stone objects can be removed or inhibited by techniques that include chemical methods (traditional biocides and nanoparticles), physical methods (mechanical removal, UV irradiation, gamma radiation, laser cleaning, heat shocking, microwaves, and dry ice treatments) and biological methods (natural molecules with biocidal activity, enzymes, and even ones based on microorganisms) [41,42]. Studies such as those conducted by Hajipour [43], Baglioni et al. [1], David et al. [20], Caneva et al. [44], and Jurca et al. [45] show that for obtaining active surfaces against pollution and microbial contamination, hard (inorganic nanocrystals) and soft (built from molecular blocks) compounds can be successfully used, e.g., inorganic compounds such as metallic nanoparticles (gold, silver, copper) and some metal oxides (zinc, titanium, iron, and aluminium), respectively. Research has been conducted for various treatments by applying nanoparticles to various types of materials, so the paper of some old books that was impregnated with an aqueous suspension of wollastonite (30–110 nm, in gel form) led to observations underlying the inhibition of Aspergillus niger development and a decrease in the permeability [45,46,47]. Cotton strips exposed to fungi (commonly found on ancient textiles) immersed in wollastonite (30–110 nm, gel—20%) emphasise the significant limitation of Aspergillus niger activity on cotton. Taghiyari et al. [48,49,50,51,52,53,54], Terzi et al. [55], Tichi et al. [56], and Weththimuni et al. [57] have investigated the effects of heat treatment on solid nano-silver-impregnated wood species with a good perspective to apply and test the methodology for cultural heritage wood objects.
Wollastonite is environmentally known to be of no or little hazard to both humans and wildlife [58,59,60]. It has even been reported to improve the growth in some plants, and to reduce the effects of special kinds of pathogens (such as some fungi species) [61]. Epidemiological studies have long shown that there was no or little evidence of wollastonite having hazardous side effects; although, long-term exposure of workers to wollastonite dust has been shown to have some slight health implications [58,60]. No correlation of serum angiotensin-covering enzymes was found between long-term inhalation of wollastonite dust and slight pulmonary fibrosis in wollastonite workers [59].
Wollastonite applications have proven remarkable in the biomedical field as bioactivators in bone mass recovery, being easily biodegradable and insoluble in substances which help bone cells’ development and function [62]. The biocidal effects of nano-wollastonite have also been reported on other types of materials (e.g., textiles, paper, wood, etc.) [46,47,56]. In the geoconservation domain, there are studies which emphasise the efficiency of silica nanosystems as biocidal agents for the conservation of stone monuments, using the advanced biotechnology of microbiological systems for the biological cleaning of cultural heritage (CH) based on sepiolite [63].
The inhibiting effects of wollastonite on fungi have been investigated in previous studies [46,47,61,64]. However, the mechanism with which wollastonite inhibits the growth of fungi species, or at least limits the rate of mycelium growth on the substrates, is yet to be explored in further studies with an emphasis on the type and degree of enzyme secretion (Table 1).
Table 1. Literature review on applications of nanoparticles in treatments for heritage objects made of stone or which have natural stone as ornaments.
Table 1. Literature review on applications of nanoparticles in treatments for heritage objects made of stone or which have natural stone as ornaments.
PaperLocationMethods and TestsResults
Dei and Salvadori [65]LimestonesNNPs calcium hydroxide treatmentsInnovative and compatible with base material, consolidation process
D’Arienzo et al. [66]Neapolitan yellow tuffNanocomposite systems based on CloisiteProtective and consolidative
Pinna et al. [41]Archaeological area of Fiesole, ItalyTested on three stone substrates with different bioreceptivity, traditional way (tetraethylorthosilicate, methylethoxy polysiloxane, Paraloid B72, tributyltin oxide, dibutyltin dilaurate) and nanotechnology (copper nanoparticles)Prevention in biological growth;
controlling recolonisation on stone after a conservation
Licchelli et al. [67]Lecce stone, ItalyCa (OH)2 and Sr (OH)2 nanoparticles applied into the stone substrate. The chemical weathering effect of salt crystallisation of the treated samples which was evaluated through dry weight loss (DWL) testGood results as consolidating agents
Aldoasri et al. [68]Marble stone facades of historic buildings, Cairo, EgyptNanometric film over the stone surface, TiO2 nanoparticles, in an aqueous colloidal suspension, applied by spray-coatingSelf-cleaning photo-induced effects are obvious in the experiment time and 6 months later
Becerra et al. [40]Heritage stone from south of SpainTwo AgNPs syntheses have been studied;Cleaning the limestone due to the biopatina formation reduction using (Ag/TiO2) nanocomposite treatments
Bruno et al. [69]Catacombs of SS. Marcellino and Pietro (Rome, Italy)essential oils (from L. angustifolia and T. vulgaris) biofilm photosynthetic activity on frescoes stoneChemical modifications and discolouration, good results
Zarzuela et al. [70]Cultural heritage stoneCuO/SiO2 nanocomposites: a multifunctional coating for application on building stone 
Ion et al. [71]Basarabi chalk monument, RomaniaHydroxyapatite nanoparticles (HAp)Physical–chemical and mechanical rocks properties improvements
Gallo et al. [72]Stone in buildings and monumentsDisinfection procedures on natural stone using smectite and ammonium saltAntimicrobial and long-term biostatic effects
Aldosari et al. [73]Historic marble columns, EgyptNanoparticles of ZnO, dispersed in laboratory synthesised acrylic polymerBiocidal against Aspergillus niger and Penicillium sp. Studies for RH/temperature, UV aging, and mechanical deterioration
Capitelli et al. [42]Conservation of stone monuments of cultural heritageFunctional nano-hydroxyapatite methodological approach against acidic rain corrosionHAp nanoparticles and their application on stony substrates has been investigated with good results
Caneva et al. [44]Caestia Pyramid (Rome), ItalyAllelopathic properties of lichen use for stone restorationResults of the tests emphasise natural product substances are a useful in control of bio-colonisation
Xie et al. [74]Heritage object marble madeColloidal protectants based on Al2O3 and SiO2 nano-powderSelf-cleaning stone effects
Weththimuni et al. [75]Lecce stone, bricks, and marbleFor this purpose, ZrO2-doped-ZnO-PDMS nanocomposites were synthesised by in situ reactionSelf-cleaning effects
Ruffolo et al. [76]Stone heritageNNPs calcium, magnesium hydroxide and nano-silicaSuperhydrophobic properties of coatings, dirt, pollutants, and microorganisms, etc., washed out by water flowing.
The combination of light and photocatalyst generated photocatalytic effects
Weththimuni et al. [77]Three different stones (Lecce stone, Carrara marble, and brick)ZnONNPs doped with ZrO2
sol–gel, to reduce the biodeterioration of cultural heritage stone buildings		Photocatalytic properties and ZnO antibacterial activity
In the case of the sandstone and limestone blocks’ external surfaces, Rai et al. [78] and Essa and Khallaf [79] used AgNPs mixed with two types of consolidation polymers. The stones treated with silicon polymer loaded with AgNPs showed antimicrobial potential against Aspergillus niger and Streptomyces parvulus. Baglioni et al. [1], Munafo et al. [80,81], Quagliarini et al. [82,83], and De Filpo et al. [84] assessed the durability and sustainability of TiO2 nanoparticles on stone that made up cultural heritage buildings in Italy and Portugal and highlighted their photocatalytic, biocidal, and self-cleaning performance, and low environmental impact. Vasanelli et al. [85] and Zornoza-Indart and Lopez-Arce [86] have tested the stone consolidation with SiO2 nanoparticle uses. The authors point out that further studies and tests are needed regarding the risks of nanoparticles regarding their effects on human health as well as on paint materials, especially through the spreading of the particles in the atmosphere after a while. Taghiyari et al. [48,49] and Esmailpour et al. [87] studied the diverse effects in the case of wollastonite-treated medium-density fibreboard.
Research on the effectiveness of different product mixtures in slowing natural biological recolonisation has been carried out for natural stone in buildings or heritage objects made of natural stone in the long term. The study carried out by Bartoli et al. [88], demonstrates that the application of three different biocides (Algophase, Biotin R, and Preventol R80) and two water-repellent substances (hydrophase surfaces and Silo 111), can prevent microbial growth for 3 years.
Regarding the short-term biodeterioration due to algae, cyanobacteria and most bacteria nanoparticles are effective, but are not satisfactory against black fungi, for which physical methods are more effective (mechanical removal and UV, heat shock treatments); TiO2 based coatings showed efficiency limited to the short/medium term after application [89,90]. Regarding chemical methods, in laboratory conditions, classical biocides (e.g., Preventol RI 50, Biotin R, RocimaTM 103) are still the most effective [91,92], producing efficient results during cleaning procedures. Plant-based extracts show limited effectiveness against fungi [89]. In laboratory conditions, cholinium@Il based coatings have shown that the use of Il’s with 12 C chains and DBS as the anion in combination with nanosilica coatings (e.g., Nano Estel) could be effective against the colonisation of black fungi for a period of time of 30 months [90].

3. Materials and Methods

The three-façade, Secession-style building known as the Markovits-Mathéser house, was designed by the architect Frigyes Spiegel in 1911 and commissioned by Markovits Sándor and Mathéser Sámuel [93,94,95]. Located at the intersection of two streets on a trapezoidal plot, it is one of the most interesting buildings in Oradea Municipality (Figure 1). The construction, that surrounds a small courtyard, stands out for the quality of the execution of the façades, for its elegance, size, volume, and for the use of different textures and materials. The access from Aurel Lazăr street is made through a spacious semicircular dome, strongly outlined by a carved wooden roof covered with shingle [94,95].
The ornamental stone is a fossiliferous limestone, having a real value for the present experiment. Thus, the collection of samples took place after the start of the renovation works of the house, they were collected from two distinct points on the main facade of the monument (Figure 2).
Raw limestone is found on the façade of the basement and second floor of the building, while on the ground floor, exposed brick alternates with plastered sections, and on the upper floors there are exposed brick, wooden elements, stucco mouldings and plastered areas [94]. The rock samples were taken during the renovation works of the building, using a scalpel, gently detaching, from crack lines, small pieces of rock from the basal part of the building. The operation was carried out so that the process was minimally invasive. Next, they were cut to the following size (L × W × H (mm)): R1 23/22/7 mm; R2 22/21/6 mm; sample 1: P1 20/20/5 mm; and sample 2: P2 21/20/5 mm. The samples had the following weights (g): R1: 9.34 g; R2: 8.42 g; P1: 6.69 g; and P2: 7.44 g (Table 2).
Two types of fungi were applied to the samples taken, namely, Aspergillus spp. and Cladosporium spp. The reason for choosing the two types of inoculated fungi was that they are within the fungal group dominated by hyphomycetes (Alternaria, Cladosporium, Ulocladium, Epicoccum, Aureobasidium), which in temperate and humid environments are the main colonisers of stone, contributing to stone erosion and disintegration, discolourations, etc. At the same time, Cladosporium spp. is the main fungi found on rock supports of stone monuments made of granite, calcarenite, limestone, sandstone, marble, etc. [24,26,37,95,96,97,98,99,100] (Figure 3).
Chemoorganotrophic fungi such as Aspergillus spp. can survive on the surfaces of a wide range of stones from stone artifacts and buildings, such as limestone, granite, marble, sandstone, andesite, gneiss, and quartz in different types of climates [101], especially on the stones’ surfaces, but because of the hyphal growth can also penetrate into the stone. Aspergillus spp. are dominant on the surfaces of buildings and stone artifacts from temperate climates: Crimea [28], United Kingdom [102], Slovakia [103], Poland [104], Serbia [105], Mediterranean Palermo, Italy [106], and from temples in humid climates such as in Cambodia [107,108].
The aqueous suspension of wollastonite used in this study was prepared by the Vard Manufacturing Company, Birjand, Iran. Based on the producer, it was a mixture of nano- (30%) and micro-sized (70%) wollastonite needles. This mixture was chosen to decrease the production costs and increase commercialisation of the compound, in case positive results were achieved [50,87]. The composition of the aqueous suspension of wollastonite is presented in Table 3. Samples without wollastonite gel content were also used for comparison purposes.
Fungal inoculation on day 1 was performed according to the data above, after immersing the upper surface of the stone in sterile distilled water. This stage was carried out to favour both the inoculation and the optimal development of the selected fungi. The colonies of Cladosporium spp. and Aspergillus spp. were previously isolated on Sabouraud and Agar Csapek culture media as subcultures, respectively.
Samples inoculated with Cladosporium spp. and Aspergillus spp. were isolated separately in two special incubation boxes equipped with mini-wells for distilled water, to create an environment favourable to fungal development, but also to reduce the risk of contamination with spores of other moulds possibly existing in the air during the handling of working materials (Figure 4 and Figure 5).
The inoculation of the two species of fungi on the natural rock samples was followed by a 72 h incubation period at a temperature of 23 ± 2 °C and humidity of 60 ± 2%, monitored using a calibrated thermohygrometer (Figure 6).
On day 4, a thin layer of the aqueous suspension of wollastonite was applied to the fungal-inoculated surface of the samples using brushes (72 h after fungal inoculation), and the samples were weighed before and after applying the gel. The amount of gel applied was different (0.06 g gel was applied on sample no. 1 and 0.14 g on sample no. 2) depending on the shape, size, and unevenness of the tested surface.
The last weighing took place after the drying of the gel (48 h after applying it). The samples were handed over under appropriate transport conditions on day 6 for additional study procedures.
In order to quantify the inhibitory effect of the aqueous suspension of wollastonite on the fungi, at the level of the sample surfaces, two sets of SEM grayscale 300× magnifier images were used in the segmentation procedure, with dimensions of 417.97 µm × 292.8 µm (1279 × 896 pixels), and with pixel sizes of 0.3268 × 0.3268 µm2. Each set contained two images: one related to the samples from the third day, after inoculation with the fungi, and one corresponding to the samples after applying the gel. The scanning electron microscope used was a Hitachi SU8230 cold field emission gun STEM (Chiyoda, Tokyo, Japan).
The trainable WEKA segmentation (TWS) plugin based on the Waikato Environment for Knowledge Analysis (WEKA) toolsets was used for image segmentation, implemented in ImageJ, an open source application, considered a standard work tool in biological studies [109]. TWS, as shown by Arganda-Carreras et al. [110], is a tool that practically transforms classic segmentation into a pixel-level classification, based on training samples used by a selected classifier. We used random forest, a machine learning classifier [111], in the fast random forest variant, with default settings for training features (Gaussian blur, Hessian, membrane projections, Sobel filter, difference of Gaussians), plus one filter for texture (median filter) and one filter for noise reduction (Kuwahara filter). A training dataset was built for each image, with two to three segmentation classes for Aspergillus spp. and three to four classes for Cladosporium spp., depending on their complexity. Before classification, the images were subjected to some initial processing operations (set scale, cropping, contrast enhancement), according to the workflows presented in the literature [112,113,114,115]. Accuracy assessment of the models obtained after training the classifier was performed in WEKA with a 10-fold stratified cross-validation test; the following performance measures being selected: correctly classified instances (CCI), kappa coefficient (k), precision (P), and recall (R) (Table 4). In addition, in order to obtain a comparative table regarding the accuracy of the classified images, new sets of training samples were built in the ENVI 5.3 software, independent of the first ones, being used to generate performance metrics similar to those in WEKA using the confusion matrix method: overall accuracy (OA), producer accuracy (PA), user accuracy (UA), and kappa coefficient (k). Previously, the basic and classified images were transferred to ENVI based on the plane coordinates (x–y), and those classified with TWS were reconverted into the ENVI classification.
Table 4. Performance metrics used in this study.
Table 4. Performance metrics used in this study.
Accuracy Measures from WEKAAccuracy Measures from ENVIDefinition, Notes
Correctly Classified Instances (CCI)Overall Accuracy (OA)Proportion of pixels correctly classified [116].
Kappa Coefficient (k)Kappa Coefficient (k)It expresses the agreement (correlation) between the performed classification (pre-dictated classes) and the dataset with the true value. It is the proportion of agreement after chance agreement is removed from consideration [117].
Recall (R)Producer Accuracy (PA)Ratio between the number of pixels correctly identified as belonging to a class and the total number of pixels of the respective class in the training dataset [118].
Precision (P)User Accuracy (UA)Ratio between the number of pixels correctly identified as belonging to a class and the total number of pixels labeled in the classification as belonging to the respective class [118].
In addition to the previously mentioned analyses, the X-ray diffraction technique was also applied to the rock samples collected from the facade of the Markovits-Mathéser house. This is an analytical technique for characterising solid materials in order to extract and characterise the crystalline structure of the analysed samples. Powder X-ray diffraction patterns were obtained using a Bruker D8 Advance diffractometer with CuKα1 monochromatic radiation (λ = 1.5405980 Å) filtered with a germanium monochromator. The diffractometer is equipped with a LINXEYE detector and X-ray tube operating at 40 kV and 40 mA. A scanning rate of 0.05°/s was employed for data collection with the DIFFRAC plus XRD Commander programs’ package, at room temperature.

4. Results and Discussions

Following the SEM image analysis, it seems that there are no visible mycelia of Cladosporium spp. on the specimens after applying the aqueous suspension of wollastonite (the needle form of wollastonite rods can also seen (Figure 7f,j)). It is hypothesised that the hydrophilicity of the aqueous suspension of wollastonite resulted in the absorption of water in the substrate, which in turn resulted in drying out and surface breakage of the specimens (Figure 7j). Aspergillus spp. is still visible (Figure 7i), but the aqueous suspension of wollastonite is dominant (central part of the image in Figure 7i); a few superficial cracks are visible too.
Since rocks, soils, clay, and dust samples have a mineral content with a high crystallinity, powder X-ray diffraction is a suitable analysis method to highlight the component phases. The diffraction pattern of the starting sample shows a high degree of crystallinity and is presented in Figure 8. The mineral composition comprises two distinct phases, namely, calcium carbonate (CaCO3, which is denoted by C) and silicon dioxide (SiO2, denoted by Q and found in the form of quartz). It can be observed that the calcium carbonate is the dominant component, while quartz displays only three diffraction lines, at 2Ɵ = 20.7°, 26.5°, and 50.0°.
After inoculating the starting material with the two types of fungi and after applying the aqueous suspension of wollastonite layer, a second powder X-ray diffraction analysis was performed, the diagrams being illustrated in Figure 9. The presence of the two phases (calcite and quartz) as in the starting sample can be noted, and also an additional phase assigned to wollastonite (CaSiO3, denoted by W) [119]. There is also an amorphous component that can be distinguished by the halo between 2Ɵ = 17–26°, which appears due to the applied gel.
For the SEM image of the sample inoculated with Aspergillus spp. (Figure 10a), the segmentation reveals that 3 days after inoculation, 59.33% (Table 5) of the sample surface is occupied by Aspergillus. After applying the gel (Figure 10b), only 2.23% of the surface shows this species of fungi, while the aqueous suspension of wollastonite was identified on 88% of the surface.
In the case of the SEM images corresponding to the sample where Cladosporium spp. was inoculated (Figure 11a), and then the aqueous suspension of wollastonite was applied (Figure 11b), the segmentations indicate that after 3 days, 36.6% of the sample surface was occupied by this genus of fungi (Table 6), and after applying the gel, Cladosporium spp. disappears almost completely (0.25% weight of the sample surface). The aqueous suspension of wollastonite layer was identified on 85.7% of the sample.
Practically, the data extracted from the segmented images provide information related to the effect on the surface that the aqueous suspension of wollastonite has on the fungi taken in the experiment.
Regarding the accuracy of the achieved segmentations, the values for the accuracy measures presented comparatively in Table 6 are an argument for their quality and for the robustness of the models generated by the random forest classifier. The average values for the accuracy indicators used for these segmentations exceed 90%, which means a very high accuracy [120].
Although promising results were achieved in hindering the growth of the two troublesome fungi on structural stones in ancient monuments, further studies should be carried out before coming to a firm and concrete conclusion as to the effectiveness of wollastonite gel. The enzyme content should be measured in the fungi, and the substrate brushed with different levels of wollastonite gel to see if there is a significant decreasing trend correlated with the increasing wollastonite content. The measurement of the enzyme content can also clarify, or at least give us some clues, on the mechanism of action of the aqueous suspension of wollastonite against fungi. Moreover, visual observations of the growth of the fungi should be made at different intervals to find out if the hindering effects of the aqueous suspension of wollastonite can also be effective over longer durations. In addition to the above mentioned further studies, a suitable fixation component should be used to prevent the wollastonite nano- and micro-needles from being washed out or wiped out if used in situ, and not to interfere with its desirable antifungal function as well.

5. Conclusions

Scanning electron microscope (SEM) and electron dispersive X-ray spectroscopy (EDX) analyses of treated stone demonstrated the existence of nanocomposite structures containing elements. Polymers functionalised with an aqueous suspension of wollastonite can be used not only as potent biocides, but also for the consolidation of historic monuments and artifacts [79]. The hydrophilicity of the aqueous suspension of wollastonite resulted in the absorption of water in the substrate, which in turn resulted in the drying out and surface breakage of the specimens. During the 48 h after the application of the gel, the research underlines that there are good pre-requisites for the aqueous suspension of wollastonite to have a biocidal effect on Aspegillus spp. and Cladosporium spp. when applied to natural stone in the construction of heritage buildings in temperate climates. Its application is easy using a brush, in a thin layer, being at the same time a green and ecofriendly potent biocide, with a price that is not very high.
The performance and protection of natural stone materials can be improved by nanotechnology, with its superhydrophobic and photocatalytic effects being emphasised especially in recent studies. Experiments should be continued over a long period of time, with intensified testing on the long-term impact of such applied materials (nanoparticles) and the protective properties imparted to natural ornamental rock in buildings, but also on the impact of nanoparticles on the environment and human health [76,79]. The aging of works of art sometimes leads to the release of nanoparticles into the environment, therefore, future experiments should consider stabilising the nanoparticles on treated works of art, without influencing their integrity.

Author Contributions

Conceptualization, D.C.I., H.R.T. and P.D.; Methodology, A.I., L.B., T.H.H. and T.C.; Software, L.B. and B.S.; Validation, A.C.P. and N.H.; Writing: original draft preparation, D.C.I., A.T., A.I., L.B.-T. and R.K.D.; Writing: review and editing, M.A.H., T.C. and A.C.P.; Visualization, D.C.I. and T.H.H.; Supervision, D.C.I. and H.R.T. All authors have read and agreed to the published version of the manuscript.

Funding

This work was supported by the Deanship of Scientific Research, Vice Presidency for Graduate Studies and Scientific Research, King Faisal University, Saudi Arabia (Grant No. 3726).

Institutional Review Board Statement

Not applicable.

Informed Consent Statement

Not applicable.

Data Availability Statement

The data presented in this study may be obtained on request from the corresponding author.

Acknowledgments

The research undertaken was made possible by the equal scientific involvement of all the authors concerned.

Conflicts of Interest

The authors declare no conflict of interest.

References

  1. Baglioni, P.; Carretti, E.; Chelazzi, D. Nanomaterials in Art Conservation. Nat. Nanotechnol. 2015, 10, 287–290. [Google Scholar] [CrossRef]
  2. Fistos, T.; Fierascu, I.; Fierascu, R.C. Recent Developments in the Application of Inorganic Nanomaterials and Nanosystems for the Protection of Cultural Heritage Organic Artifacts. Nanomaterials 2022, 12, 207. [Google Scholar] [CrossRef]
  3. Pope, G.A.; Meierding, T.C.; Paradise, T.R. Geomorphology’s Role in the Study of Weathering of Cultural Stone. Geomorphology 2002, 47, 211–225. [Google Scholar] [CrossRef]
  4. Siegesmund, S.; Weiss, T.; Vollbrecht, A. Natural stone, weathering phenomena, conservation strategies and case studies: Introduction. Geol. Soc. Lond. Spec. Publ. 2002, 205, 1–7. [Google Scholar] [CrossRef]
  5. Huggett, R. Fundamentals of Geomorphology; Taylor & Francis: Manchester, UK, 2016. [Google Scholar]
  6. Zhang, G.; Gong, C.; Gu, J.; Katayama, Y.; Someya, T.; Gu, J.-D. Biochemical Reactions and Mechanisms Involved in the Biodeterioration of Stone World Cultural Heritage under the Tropical Climate Conditions. Int. Biodeterior. Biodegrad. 2019, 143, 104723. [Google Scholar] [CrossRef]
  7. Wild, B.; Gerrits, R.; Bonneville, S. The Contribution of Living Organisms to Rock Weathering in the Critical Zone. NPJ Mater. Degrad. 2022, 6, 98. [Google Scholar] [CrossRef]
  8. Sardella, A.; Palazzi, E.; von Hardenberg, J.; Del Grande, C.; De Nuntiis, P.; Sabbioni, C.; Bonazza, A. Risk Mapping for the Sustainable Protection of Cultural Heritage in Extreme Changing Environments. Atmosphere 2020, 11, 700. [Google Scholar] [CrossRef]
  9. Aktas, Y.D. Cities and Urban Heritage in the Face of a Changing Climate. Atmosphere 2021, 12, 1007. [Google Scholar] [CrossRef]
  10. Vyshkvarkova, E.; Sukhonos, O. Climate Change Impact on the Cultural Heritage Sites in the European Part of Russia over the Past 60 Years. Climate 2023, 11, 50. [Google Scholar] [CrossRef]
  11. IPCC. Climate Change 2022: Mitigation of Climate Change. In Contribution of Working Group III to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change; Shukla, P.R., Skea, J., Slade, R., Al Khourdajie, A., van Diemen, R., McCollum, D., Pathak, M., Some, S., Vyas, P., Fradera, R., et al., Eds.; Cambridge University Press: Cambridge, UK; New York, NY, USA, 2022. [Google Scholar] [CrossRef]
  12. Dumitrescu, A.; Bojariu, R.; Birsan, M.-V.; Marin, L.; Manea, A. Recent Climatic Changes in Romania from Observational Data (1961–2013). Theor. Appl. Climatol. 2015, 122, 111–119. [Google Scholar] [CrossRef]
  13. Marin, L.; Birsan, M.-V.; Bojariu, R.; Dumitrescu, A.; Micu, D.M.; Manea, A. An Overview of Annual Climatic Changes in Romania: Trends in Air Temperature, Precipitation, Sunshine Hours, Cloud Cover, Relative Humidity and Wind Speed during the 1961–2013 Period. Carpathian J. Earth Environ. Sci. 2014, 9, 253–258. [Google Scholar]
  14. UNESCO (United Nations Educational, Scientific and Cultural Organization). The UNESCO Recommendation on the Historic Urban Landscape. Report of the Second Consultation on its Implementation by Member States. 2019. Available online: https://whc.unesco.org/document/172639 (accessed on 20 August 2023).
  15. Zeleňáková, M.; Purcz, P.; Hlavatá, H.; Blišťan, P. Climate Change in Urban Versus Rural Areas. Procedia Eng. 2015, 119, 1171–1180. [Google Scholar] [CrossRef]
  16. Masson, V.; Lemonsu, A.; Hidalgo, J.; Voogt, J. Urban Climates and Climate Change. Annu. Rev. Environ. Resour. 2020, 45, 411–444. [Google Scholar] [CrossRef]
  17. Hamdi, R.; Kusaka, H.; Doan QVan Cai, P.; He, H.; Luo, G.; Kuang, W.; Caluwaerts, S.; Duchêne, F.; Van Schaeybroek, B.; Termonia, P. The State-of-the-Art of Urban Climate Change Modeling and Observations. Earth Syst. Environ. 2020, 4, 631–646. [Google Scholar] [CrossRef]
  18. Liu, Z.; Zhan, W.; Bechtel, B.; Voogt, J.; Lai, J.; Chakraborty, T.; Wang, Z.-H.; Li, M.; Huang, F.; Lee, X. Surface Warming in Global Cities Is Substantially More Rapid than in Rural Background Areas. Commun. Earth Environ. 2022, 3, 219. [Google Scholar] [CrossRef]
  19. Warscheid, T.; Braams, J. Biodeterioration of Stone: A Review. Int. Biodeterior. Biodegrad. 2000, 46, 343–368. [Google Scholar]
  20. David, M.E.; Ion, R.-M.; Grigorescu, R.M.; Iancu, L.; Andrei, E.R. Nanomaterials Used in Conservation and Restoration of Cultural Heritage: An Up-to-Date Overview. Materials 2020, 13, 2064. [Google Scholar] [CrossRef]
  21. Bungau, C.C.; Prada, I.F.; Prada, M.; Bungau, C. Design and operation of construction: A healthy living environment—Parametric studies and new solutions. Sustainability 2019, 11, 6824. [Google Scholar] [CrossRef]
  22. Franco-Castillo, I.; Hierro, L.; de la Fuente, J.M.; Seral-Ascaso, A.; Mitchell, S.G. Perspectives for Antimicrobial Nanomaterials in Cultural Heritage Conservation. Chem 2021, 7, 629–669. [Google Scholar] [CrossRef]
  23. Caneva, G.; Nugari, M.P.; Salvadori, O. Plant Biology for Cultural Heritage: Biodeterioration and Conservation; Getty Publications: Los Angeles, CA, USA, 2008; ISBN 9780892369393. [Google Scholar]
  24. Sterflinger, K. Fungi: Their Role in Deterioration of Cultural Heritage. Fungal Biol. Rev. 2010, 24, 47–55. [Google Scholar] [CrossRef]
  25. Gadd, G.M. Geomicrobiology of the Built Environment. Nat. Microbiol. 2017, 2, 16275. [Google Scholar] [CrossRef]
  26. De Leo, F.; Marchetta, A.; Urzì, C. Black Fungi on Stone-Built Heritage: Current Knowledge and Future Outlook. Appl. Sci. 2022, 12, 3969. [Google Scholar] [CrossRef]
  27. De la Torre, M.A.; Gomez-Alarcon, G.; Melgarejo, P.; Saiz-Jimenez, C. Fungi in Weathered Sandstone from Salamanca Cathedral, Spain. Sci. Total Environ. 1991, 107, 159–168. [Google Scholar] [CrossRef]
  28. Badalyan, A.G.; Gorbushina, A.A.; Krumbein, W.E. Physical and Microbiological Investigations of Rock Weathering at Hellenic Excavation Sites on the Crimean Peninsula. In Proceedings of the Eighth International Congress on Deterioration and Conservation of Stone, Berlin, Germany, 30 September–4 October 1996. [Google Scholar]
  29. Dornieden, T.; Gorbushina, A.A.; Krumbein, W.E. Patina: Physical and chemical interactions of sub-aerial biofilms with objects of art. In Of Microbes and Art—The Role of Microbial Communities in the Degradation and Protection of Cultural Heritage; Springer: Boston, MA, USA, 2000; pp. 105–119. [Google Scholar]
  30. Gorbushina, A.A.; Krumbein, W.E.; Hamman, C.H.; Panina, L.; Soukharjevski, S.; Wollenzien, U. Role of black fungi in color change and biodeterioration of antique marbles. Geomicrobiol. J. 1993, 11, 205–221. [Google Scholar] [CrossRef]
  31. Caneva, G.; Maggi, O.; Nugari, M.P.; Pietrini, A.M.; Piervittori, V.; Ricci, S.; Roccardi, A. The biological aerosol as a factor of biodeterioration. In Cultural Heritage and Aerobiology—Methods and Measurement Techniques for Biodeterioration Monitoring; Mandrioli, P., Caneva, G., Sabbioni, C., Eds.; Springer Science+Business Media: Dordrecht, The Netherlands, 2003; pp. 3–29. [Google Scholar]
  32. Olteanu, I. Piatra în Patrimonioul Românesc: Degradări Specifice și Tratamente Adecvate; Editura ACS: București, Romania, 2015; 335p, ISBN 978-606-93583-8-2. [Google Scholar]
  33. Cinteză, L.O.; Tănase, M.A. Multifunctional ZnO Nanoparticle: Based Coatings for Cultural Heritage Preventive Conservation. In Thin Films; Ares, A.E., Ed.; IntechOpen: London, UK, 2020; 20p. [Google Scholar]
  34. Savković, Ž.; Unković, N.; Stupar, M.; Franković, M.; Jovanović, M.; Erić, S.; Šarić, K.; Stanković, S.; Dimkić, I.; Vukojević, J.; et al. Diversity and biodeteriorative potential of fungal dwellers on ancient stone stela. Int. Biodeterior. Biodegrad. 2016, 115, 212–223. [Google Scholar] [CrossRef]
  35. Chelazzi, D.; Camerini, R.; Giorgi, R.; Baglioni, P. Nanomaterials for the Consolidation of Stone Artifacts. In Advanced Materials for the Conservation of Stone; Hosseini, M., Karapanagiotis, I., Eds.; Springer: Cham, Switzerland, 2019; pp. 151–173. [Google Scholar] [CrossRef]
  36. Bogdan, A.; Chambre, D.; Copolovici, D.M.; Bungau, T.; Bungau, C.C.; Copolovici, L. Heritage Building Preservation in the Process of Sustainable Urban Development: The Case of Brasov Medieval City, Romania. Sustainability 2022, 14, 6959. [Google Scholar] [CrossRef]
  37. Pinna, D.; Salvadori, O. Stone and related materials. In Plant Biology for Cultural Heritage: Biodeterioration and Conservation; Caneva, G., Nugari, M.P., Nugari, M.P., Salvadori, O., Eds.; Getty Conservation Institute: Los Angeles, CA, USA, 2008; pp. 128–144. [Google Scholar]
  38. Barakat, M.A.E.-F.; Kumar, R. Nanomaterials for Environmental Applications; CRC Press: Boca Raton, FL, USA, 2022; ISBN 9781000532852. [Google Scholar]
  39. Kanth, A.P.; Soni, A.K. Application of Nanocomposites for Conservation of Materials of Cultural Heritage. J. Cult. Herit. 2023, 59, 120–130. [Google Scholar] [CrossRef]
  40. Becerra, J.; Zaderenko, A.P.; Gómez-Morón, M.A.; Ortiz, P. Nanoparticles Applied to Stone Buildings. Int. J. Archit. Heritage Conserv. Anal. Restor. 2021, 15, 1320–1335. [Google Scholar] [CrossRef]
  41. Pinna, D.; Salvadori, B.; Galeotti, M. Monitoring the Performance of Innovative and Traditional Biocides Mixed with Consolidants and Water-Repellents for the Prevention of Biological Growth on Stone. Sci. Total Environ. 2012, 423, 132–141. [Google Scholar] [CrossRef]
  42. Capitelli, F.; Dida, B.; Ventura, G.D.; Baldassarre, F.; Capelli, D.; Senesi, G.S.; Mele, A.; Siliqi, D. Functional Nano-Hydroxyapatite for Applications in Conservation of Stony Monuments of Cultural Heritage. In Proceedings of the 2nd International Online Conference on Crystals, Bari, Italy, 10–20 November 2020; MDPI: Basel, Switzerland, 2021. [Google Scholar]
  43. Hajipour, M.J.; Fromm, K.M.; Ashkarran, A.A.; Jimenez de Aberasturi, D.; de Larramendi, I.R.; Rojo, T.; Serpooshan, V.; Parak, W.J.; Mahmoudi, M. Antibacterial Properties of Nanoparticles. Trends Biotechnol. 2012, 30, 499–511. [Google Scholar] [CrossRef]
  44. Caneva, G.; Fidanza, M.R.; Tonon, C.; Favero-Longo, S.E. Biodeterioration Patterns and Their Interpretation for Potential Applications to Stone Conservation: A Hypothesis from Allelopathic Inhibitory Effects of Lichens on the Caestia Pyramid (Rome). Sustain. Sci. Pract. Policy 2020, 12, 1132. [Google Scholar] [CrossRef]
  45. Jurcă, M.C.; Bembea, M.; Kozma, K.; Şandor, M.I.; Negrean, R.A.; Dobjanschi, L.; Cuc, E.A.; Petcheşi, C.D.; Jurcă, A.D. Empty sella associated with growth hormone deficiency and polydactyly. Rom. J. Morphol. Embryol. 2018, 59, 381–384. [Google Scholar] [PubMed]
  46. Taghiyari, H.R.; Majidinajafabadi, R.; Vahidzadeh, R. Wollastonite to Hinder Growth of Aspergillus Niger Fungus on Cotton Textile. An. Da Acad. Bras. De Cienc. 2018, 90, 2797–2804. [Google Scholar] [CrossRef]
  47. Taghiyari, H.R.; Kalantari, A.; Kalantari, A.; Avramidis, S. Effect of Wollastonite Nanofibers and Exposure to Aspergillus Niger Fungus on Air Flow Rate in Paper. Measurement 2019, 136, 307–313. [Google Scholar] [CrossRef]
  48. Taghiyari, H.R.; Enayati, A.; Gholamiyan, H. Effects of nano-silver impregnation on brittleness, physical and mechanical properties of heat-treated hardwoods. Wood Sci. Technol. 2013, 47, 467–480. [Google Scholar] [CrossRef]
  49. Taghiyari, H.R. Effects of heat-treatment on permeability of untreated and nanosilver-impregnated native hardwoods. MaderasCienc. Tecnol. 2013, 15, 183–194. [Google Scholar] [CrossRef]
  50. Taghiyari, H.R.; Samandarpour, A. Effects of nanosilver-impregnation and heat treatment on coating pull-off adhesion strength on solid wood. Drvna Ind. 2015, 66, 321–327. [Google Scholar] [CrossRef]
  51. Taghiyari, H.R.; Esmailpour, A.; Papadopoulos, A. Paint pull-off strength and permeability in nanosilver-impregnated and heat-treated beech wood. Coatings 2019, 9, 723. [Google Scholar] [CrossRef]
  52. Taghiyari, H.R.; Bayani, S.; Militz, H.; Papadopoulos, A.N. Heat treatment of pine wood: Possible effect of impregnation with silver nanosuspension. Forests 2020, 11, 466. [Google Scholar] [CrossRef]
  53. Taghiyari, H.R.; Esmailpour, A.; Majidi, R.; Hassani, V.; Abdolah Mirzaei, R.; Farajpour Bibalan, O.; Papadopoulos, A.N. The effect of silver and copper nanoparticles as resin fillers on less-studied properties of UF-based particleboards. Wood Mater. Sci. Eng. 2020, 17, 317–327. [Google Scholar] [CrossRef]
  54. Taghiyari, H.R.; Ilies, D.C.; Antov, P.; Vasile, G.; Majidinajafabadi, R.; Lee, S.H. Effects of Nanosilver and Heat Treatment on the Pull-Off Strength of Sealer-Clear Finish in Solid Wood Species. Polymers 2022, 14, 5516. [Google Scholar] [CrossRef] [PubMed]
  55. Terzi, E.; Kartal, S.N.; Yılgör, N.; Rautkari, L.; Yoshimura, T. Role of Various Nano-Particles in Prevention of Fungal Decay, Mold Growth and Termite Attack in Wood, and Their Effect on Weathering Properties and Water Repellency. Int. Biodeterior. Biodegrad. 2016, 107, 77–87. [Google Scholar] [CrossRef]
  56. Tichi, A.H.; Bari, E.; Nicholas, D.D. How Nano-Wollastonite Can Change the Fundamental Properties of a Wood Fibre and Rice Straw Composites? IET Nanobiotechnol. 2018, 12, 1027–1030. [Google Scholar] [CrossRef] [PubMed]
  57. Weththimuni, M.L.; Capsoni, D.; Malagodi, M.; Licchelli, M. Improving Wood Resistance to Decay by Nanostructured ZnO-Based Treatments. J. Nanomater. 2019, 2019, 6715756. [Google Scholar] [CrossRef]
  58. Huuskonen, M.S.; Järvisalo, J.; Koskinen, H.; Nickels, J.; Räsänen, J.; Asp, S. Preliminary results from a cohort of workers exposed to wollastonite in a Finnish limestone quarry. Scand. J. Work. Environ. Health 1983, 9, 169–175. Available online: http://www.jstor.org/stable/40964396 (accessed on 1 September 2023). [CrossRef] [PubMed]
  59. Huuskonen, M.S.; Tossavainen, A.; Koskinen, H.; Zitting, A.; Korhonen, O.; Nickels, J.; Korhonen, K.; Vaaranen, V. Wollastonite exposure and lung fibrosis. Environ. Res. 1983, 30, 291–304. [Google Scholar] [CrossRef]
  60. Maxim, L.D.; McConnell, E.E. A Review of the Toxicology and Epidemiology of Wollastonite. Inhal. Toxicol. 2005, 17, 451–466. [Google Scholar] [CrossRef]
  61. Aitken, E. Analyses of the Effect of Silicon on Fusarium Wilt on Banana. 2010. Available online: https://espace.library.uq.edu.au/view/UQ:270994 (accessed on 1 September 2023).
  62. Abd Rashid, R.; Shamsudin, R.; Abdul Hamid, M.A.; Jalar, A. In-vitro bioactivity of wollastonite materials derived from limestone and silica sand. Ceram. Int. 2014, 40, 6847–6853. [Google Scholar] [CrossRef]
  63. Bosch-Roig, P.; Lustrato, G.; Zanardini, E.; Ranalli, G. Biocleaning of Cultural Heritage stone surfaces and frescoes: Which delivery system can be the most appropriate? Ann. Microbiol. 2014, 65, 1227–1241. [Google Scholar] [CrossRef]
  64. Karimi, A.; Taghiyari, H.R.; Fattahi, A.; Karimi, S.; Ebrahimi, G.; Tarmian, A. Effects of Wollastonite Nanofibers on Biological Durability of Poplar Wood (Populus nigra) against Trametes versicolor. BioResources 2013, 8, 4134–4141. [Google Scholar] [CrossRef]
  65. Dei, L.; Salvadori, B. Nanotechnology in Cultural Heritage Conservation: Nanometric Slaked Lime Saves Architectonic and Artistic Surfaces from Decay. J. Cult. Herit. 2006, 7, 110–115. [Google Scholar] [CrossRef]
  66. D’Arienzo, L.; Scarfato, P.; Incarnato, L. New Polymeric Nanocomposites for Improving the Protective and Consolidating Efficiency of Tuff Stone. J. Cult. Herit. 2008, 9, 253–260. [Google Scholar] [CrossRef]
  67. Licchelli, M.; Malagodi, M.; Weththimuni, M.; Zanchi, C. Nanoparticles for Conservation of Bio-Calcarenite Stone. Appl. Phys. A Mater. Sci. Process. 2014, 114, 673–683. [Google Scholar] [CrossRef]
  68. Aldoasri, M.A.; Darwish, S.S.; Adam, M.A.; Elmarzugi, N.A.; Ahmed, S.M. Protecting of Marble Stone Facades of Historic Buildings Using Multifunctional TiO2 Nanocoatings. Sustain. Sci. Pract. Policy 2017, 9, 2002. [Google Scholar] [CrossRef]
  69. Bruno, L.; Rugnini, L.; Spizzichino, V.; Caneve, L.; Canini, A.; Ellwood, N.T.W. Biodeterioration of Roman Hypogea: The Case Study of the Catacombs of SS. Marcellino and Pietro (Rome, Italy). Ann. Microbiol. 2019, 69, 1023–1032. [Google Scholar] [CrossRef]
  70. Zarzuela, R.; Carbú, M.; Gil, M.L.A.; Cantoral, J.M.; Mosquera, M.J. CuO/SiO2 Nanocomposites: A Multifunctional Coating for Application on Building Stone. Mater. Des. 2017, 114, 364–372. [Google Scholar] [CrossRef]
  71. Ion, R.M.; Fierăscu, R.C.; Fierăscu, I.; Bunghez, I.R.; Ion, M.L.; Caruţiu-Turcanu, D.; Teodorescu, S.; Rădiţoiu, V. Stone Monuments Consolidation with Nanomaterials. Key Eng. Mater. 2015, 660, 383–388. [Google Scholar] [CrossRef]
  72. Gallo, C.; Rizzo, P.; Guerra, G. Intercalation Compounds of a Smectite Clay with an Ammonium Salt Biocide and Their Possible Use for Conservation of Cultural Heritage. Heliyon 2019, 5, e02991. [Google Scholar] [CrossRef]
  73. Aldosari, M.A.; Darwish, S.S.; Adam, M.A.; Elmarzugi, N.A.; Ahmed, S.M. Using ZnO Nanoparticles in Fungal Inhibition and Self-Protection of Exposed Marble Columns in Historic Sites. Archaeol. Anthropol. Sci. 2019, 11, 3407–3422. [Google Scholar] [CrossRef]
  74. Xie, Z.; Duan, Z.; Zhao, Z.; Li, R.; Zhou, B.; Yang, D.; Hu, Y. Nano-Materials Enhanced Protectants for Natural Stone Surfaces. Herit. Sci. 2021, 9, 122. [Google Scholar] [CrossRef]
  75. Weththimuni, M.L.; Chobba, M.B.; Sacchi, D.; Messaoud, M.; Licchelli, M. Durable Polymer Coatings: A Comparative Study of PDMS-Based Nanocomposites as Protective Coatings for Stone Materials. Chemistry 2022, 4, 60–76. [Google Scholar] [CrossRef]
  76. Ruffolo, S.A.; La Russa, M.F. Nanoparticles in the Field of Built Heritage Restoration: Challenges and Limits. In Handbook of Cultural Heritage Analysis; D’Amico, S., Venuti, V., Eds.; Springer International Publishing: Cham, Switzerland, 2022; pp. 1033–1050. ISBN 9783030600167. [Google Scholar]
  77. Weththimuni, M.L.; Chobba, M.B.; Tredici, I.; Licchelli, M. ZrO2-doped ZnO-PDMS nanocomposites as protective coatings for the stone materials. Acta IMEKO 2022, 11, 5. [Google Scholar] [CrossRef]
  78. Rai, M.; Yadav, A.; Gade, A. Silver Nanoparticles as a New Generation of Antimicrobials. Biotechnol. Adv. 2009, 27, 76–83. [Google Scholar] [CrossRef] [PubMed]
  79. Essa, A.M.M.; Khallaf, M.K. Biological Nanosilver Particles for the Protection of Archaeological Stones against Microbial Colonization. Int. Biodeterior. 2014, 94, 31–37. [Google Scholar] [CrossRef]
  80. Munafò, P.; Quagliarini, E.; Goffredo, G.B.; Bondioli, F.; Licciulli, A. Durability of nano-engineered TiO2 self-cleaning treatments on limestone. Constr. Build. Mater. 2014, 65, 218–231. [Google Scholar] [CrossRef]
  81. Munafò, P.; Goffredo, G.B.; Quagliarini, E. TiO2-Based Nanocoatings for Preserving Architectural Stone Surfaces: An Overview. Constr. Build. Mater. 2015, 84, 201–218. [Google Scholar] [CrossRef]
  82. Quagliarini, E.; Bondioli, F.; Goffredo, G.B.; Cordoni, C.; Munafò, P. Self-cleaning and de-polluting stone surfaces: TiO2 nanoparticles for limestone. Constr. Build. Mater. 2012, 37, 51–57. [Google Scholar] [CrossRef]
  83. Quagliarini, E.; Graziani, L.; Diso, D.; Licciulli, A.; D’Orazio, M. Is Nano-TiO 2 Alone an Effective Strategy for the Maintenance of Stones in Cultural Heritage? J. Cult. Herit. 2018, 30, 81–91. [Google Scholar] [CrossRef]
  84. De Filpo, G.; Palermo, A.M.; Rachiele, F.; Nicoletta, F.P. Preventing fungal growth in wood by titanium dioxide nanoparticles. Int. Biodeterior. Biodegrad. 2013, 85, 217–222. [Google Scholar] [CrossRef]
  85. Vasanelli, E.; Calia, A.; Masieri, M.; Baldi, G. Stone Consolidation with SiO2 Nanoparticles: Effects on a High Porosity Limestone. Constr. Build. Mater. 2019, 219, 154–163. [Google Scholar] [CrossRef]
  86. Zornoza-Indart, A.; Lopez-Arce, P. Silica Nanoparticles (SiO2): Influence of Relative Humidity in Stone Consolidation. J. Cult. Herit. 2016, 18, 258–270. [Google Scholar] [CrossRef]
  87. Esmailpour, A.; Taghiyari, H.R.; Majidi, R.; Babaali, S.; Morrell, J.J.; Mohammadpanah, B. Effects of Adsorption Energy on Air and Liquid Permeability of Nanowollastonite-Treated Medium-Density Fiberboard. IEEE Trans. Instrum. Meas. 2021, 70, 1000108. [Google Scholar] [CrossRef]
  88. Bartoli, F.; Isola, D.; Casanova Municchia, A.; Kumbaric, A.; Caneva, G. Science for Art: Multi-Years’ Evaluations of Biocidal Efficacy in Support of Artwork Conservation. Front. Microbiol. 2023, 14, 1178900. [Google Scholar] [CrossRef] [PubMed]
  89. Chobba, M.B.; Weththimuni, M.L.; Messaoud, M.; Urzi, C.; Bouaziz, J.; De Leo, F.; Licchelli, M. Ag-TiO2/PDMS Nanocomposite Protective Coatings: Synthesis, Characterization, and Use as a Self-Cleaning and Antimicrobial Agent. Prog. Org. Coat. 2021, 158, 106342. [Google Scholar] [CrossRef]
  90. De Leo, F.; Marchetta, A.; Capillo, G.; Germanà, A.; Primerano, P.; Schiavo, S.L.; Urzì, C. Surface Active Ionic Liquids Based Coatings as Subaerial Anti-Biofilms for Stone Built Cultural Heritage. Coat. World 2020, 11, 26. [Google Scholar] [CrossRef]
  91. Lo Schiavo, S.; De Leo, F.; Urzì, C. Present and Future Perspectives for Biocides and Antifouling Products for Stone-Built Cultural Heritage: Ionic Liquids as a Challenging Alternative. Appl. Sci. 2020, 10, 6568. [Google Scholar] [CrossRef]
  92. Isola, D.; Bartoli, F.; Meloni, P.; Caneva, G.; Zucconi, L. Black Fungi and Stone Heritage Conservation: Ecological and Metabolic Assays for Evaluating Colonization Potential and Responses to Traditional Biocides. Appl. Sci. 2022, 12, 2038. [Google Scholar] [CrossRef]
  93. Pașca, M. Oradea 1900: Un Ghid de Arhitectură, Ed. a 3-a; Editura Argonaut: Cluj-Napoca, Romania, 2019; ISBN 978-973-109-932-3. [Google Scholar]
  94. Pașca, M. Arhitectul Frigyes Spiegel la Oradea; Editura Arca: Oradea, Romania, 2010; ISBN 978-973-1881-49-2. [Google Scholar]
  95. Santo, A.P.; Cuzman, O.A.; Petrocchi, D.; Pinna, D.; Salvatici, T.; Perito, B. Black on white: Microbial growth darkens the external marble of Florence cathedral. Appl. Sci. 2021, 11, 6163. [Google Scholar] [CrossRef]
  96. Sert, H.B.; Sümbül, H.; Sterflinger, K. Microcolonial fungi from antique marbles in Perge/Side/Termessos (Antalya/Turkey). Antonie Van Leeuwenhoek J. Microb. 2007, 91, 217–227. [Google Scholar] [CrossRef]
  97. Sazanova, K.V.; Zelenskaya, M.S.; Vlasov, A.D.; Bobir, S.Y.; Yakkonen, K.L.; Vlasov, D.Y. Microorganisms in superficial deposits on the stone monuments in Saint Petersburg. Microorganisms 2022, 10, 316. [Google Scholar] [CrossRef]
  98. Nuhoglu, Y.; Oguz, E.; Uslu, H.; Ozbek, A.; Ipekoglu, B.; Ocak, I.; Hasenekoglu, I. The accelerating effects of the microorganisms on biodeterioration of stone monuments under air pollution and continental-cold climatic conditions in Erzurum, Turkey. Sci. Total Environ. 2006, 364, 272–283. [Google Scholar] [CrossRef] [PubMed]
  99. Trovão, J.; Gil, F.; Catarino, L.; Soares, F.; Tiago, I.; Portugal, A. Analysis of fungal deterioration phenomena in the first Portuguese King tomb using a multianalytical approach. Int. Biodeterior. Biodegrad. 2020, 149, 104933. [Google Scholar] [CrossRef]
  100. Gorbushina, A.A.; Heyrman, J.; Dornieden, T.; Gonzalez-Delvalle, M.; Krumbein, W.E.; Laiz, L.; Petersen, K.; Saiz-Jimenez, C.; Swings, J. Bacterial and fungal diversity and biodeterioration problems in mural painting environments of St. Martins church (Greene–Kreiensen, Germany). Int. Biodeterior. Biodegrad. 2004, 53, 13–24. [Google Scholar] [CrossRef]
  101. Burford, E.P.; Kierans, M.; Gadd, G.M. Geomycology: Fungi in mineral substrata. Mycologist 2003, 17, 98–107. [Google Scholar] [CrossRef]
  102. Wollenzien, U.; de Hoog, G.S.; Krumbein, W.E.; Urzí, C. On the Isolation of Microcolonial Fungi Occurring on and in Marble and Other Calcareous Rocks. Sci. Total Environ. 1995, 167, 287–294. [Google Scholar] [CrossRef]
  103. Pangallo, D.; Chovanová, K.; Simonovicová, A.; Ferianc, P. Investigation of Microbial Community Isolated from Indoor Artworks and Air Environment: Identification, Biodegradative Abilities, and DNA Typing. Can. J. Microbiol. 2009, 55, 277–287. [Google Scholar] [CrossRef]
  104. Dyda, M.; Pyzik, A.; Wilkojc, E.; Kwiatkowska-Kopka, B.; Sklodowska, A. Bacterial and Fungal Diversity Inside the Medieval Building Constructed with Sandstone Plates and Lime Mortar as an Example of the Microbial Colonization of a Nutrient-Limited Extreme Environment (Wawel Royal Castle, Krakow, Poland). Microorganisms 2019, 7, 416. [Google Scholar] [CrossRef]
  105. Ljaljevic-Grbic, M.V.; Vukojevic, J.B. Role of Fungi in Biodeterioration Process of Stone in Historic Buildings. Zbornik Matice Srpske za Prirodne Nauke 2009, 116, 245–251. [Google Scholar] [CrossRef]
  106. Palla, F. Biotechnology and Cultural Heritage Conservation. In Heritage; Turcanu-Carutiu, D., Ed.; IntechOpen: London, UK, 2020; pp. 239–254. [Google Scholar]
  107. Hu, Z.; Zhang, R.; Zhu, K.; Li, D.; Jin, Y.; Guo, W.; Liu, X.; Zhang, X.; Zhang, Q. Probing the Pore Structure of the Berea Sandstone by Using X-Ray Micro-CT in Combination with ImageJ Software. Minerals 2023, 13, 360. [Google Scholar] [CrossRef]
  108. Romero, S.M.; Giudicessi, S.L.; Vitale, R.G. Is the Fungus Aspergillus a Threat to Cultural Heritage? J. Cult. Herit. 2021, 51, 107–124. [Google Scholar] [CrossRef]
  109. Vohra, S.K.; Prodanov, D. The Active Segmentation Platform for Microscopic Image Classification and Segmentation. Brain Sci. 2021, 11, 1645. [Google Scholar] [CrossRef]
  110. Arganda-Carreras, I.; Kaynig, V.; Rueden, C.; Eliceiri, K.W.; Schindelin, J.; Cardona, A.; Seung, H.S. Trainable Weka Segmentation: A Machine Learning Tool for Microscopy Pixel Classification. Bioinformatics 2017, 33, 2424–2426. [Google Scholar] [CrossRef] [PubMed]
  111. Breiman, L. Random Forests. Mach. Learn. 2001, 45, 5–32. [Google Scholar] [CrossRef]
  112. Lormand, C.; Zellmer, G.F.; Németh, K.; Kilgour, G.; Mead, S.; Palmer, A.S.; Sakamoto, N.; Yurimoto, H.; Moebis, A. Weka Trainable Segmentation Plugin in ImageJ: A Semi-Automatic Tool Applied to Crystal Size Distributions of Microlites in Volcanic Rocks. Microsc. Microanal. 2018, 24, 667–675. [Google Scholar] [CrossRef] [PubMed]
  113. Cairns, T.C.; Feurstein, C.; Zheng, X.; Zheng, P.; Sun, J.; Meyer, V. A Quantitative Image Analysis Pipeline for the Characterization of Filamentous Fungal Morphologies as a Tool to Uncover Targets for Morphology Engineering: A Case Study Using AplD in Aspergillus Niger. Biotechnol. Biofuels 2019, 12, 149. [Google Scholar] [CrossRef]
  114. Purswani, P.; Karpyn, Z.T.; Enab, K.; Xue, Y.; Huang, X. Evaluation of Image Segmentation Techniques for Image-Based Rock Property Estimation. J. Pet. Sci. Eng. 2020, 195, 107890. [Google Scholar] [CrossRef]
  115. Nazem-Bokaee, H.; Fallahianbijan, F.; Chen, D.; O’Donnell, S.M.; Carbrello, C.; Giglia, S.; Bell, D.; Zydney, A.L. Probing pore structure of virus filters using scanning electron microscopy with gold nanoparticles. J. Membr. Sci. 2018, 552, 144–152. [Google Scholar] [CrossRef]
  116. Fernandez-Carrillo, A.; Franco-Nieto, A.; Pinto-Bañuls, E.; Basarte-Mena, M.; Revilla-Romero, B. Designing a Validation Protocol for Remote Sensing Based Operational Forest Masks Applications. Comparison of Products Across Europe. Remote Sens. 2020, 12, 3159. [Google Scholar] [CrossRef]
  117. Cohen, J. A coefficient of agreement for nominal scales. Educ. Psychol. Meas. 1960, 20, 37–46. [Google Scholar] [CrossRef]
  118. Congalton, R.G. Accuracy Assessment and Validation of Remotely Sensed and Other Spatial Information. Int. J. Wildl. Fire 2001, 10, 321–328. [Google Scholar] [CrossRef]
  119. Hesse, K.-F. Refinement of the crystal structure of wollastonite-2M (parawollastonite). Z. Fur Krist. 1984, 168, 93–98. [Google Scholar] [CrossRef]
  120. Szantoi, Z.; Escobedo, F.; Abd-Elrahman, A.; Smith, S.; Pearlstine, L. Analyzing Fine-Scale Wetland Composition Using High Resolution Imagery and Texture Features. Int. J. Appl. Earth Obs. Geoinf. 2013, 23, 204–212. [Google Scholar] [CrossRef]
Minerals 13 01170 g001
Figure 1. The location of Markovits-Mathéser house within Bihor County and Oradea Municipality.
Figure 1. The location of Markovits-Mathéser house within Bihor County and Oradea Municipality.
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Figure 2. (a) Overview of the Markovits-Mathéser house; (b) the collection points of rock samples for carrying out the experiment.
Figure 2. (a) Overview of the Markovits-Mathéser house; (b) the collection points of rock samples for carrying out the experiment.
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Minerals 13 01170 g003
Figure 3. The work flowchart for carrying out the research.
Figure 3. The work flowchart for carrying out the research.
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Figure 4. Rock specimens inoculated with Cladosporium spp. (a—petri plate seeded with Cladosporium spp.; b—the seeding method of the rock samples).
Figure 4. Rock specimens inoculated with Cladosporium spp. (a—petri plate seeded with Cladosporium spp.; b—the seeding method of the rock samples).
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Minerals 13 01170 g005
Figure 5. Rock specimens inoculated with both Cladosporium spp. and Aspergillus spp.
Figure 5. Rock specimens inoculated with both Cladosporium spp. and Aspergillus spp.
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Figure 6. 72 h incubation period at a temperature of 23 ± 2 °C and humidity of 60 ± 2%.
Figure 6. 72 h incubation period at a temperature of 23 ± 2 °C and humidity of 60 ± 2%.
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Minerals 13 01170 g007
Figure 7. Scanning electron microscope images of the surfaces loaded with Aspergillus spp. and Cladosporium spp. and then treated with aqueous suspension of wollastonite.
Figure 7. Scanning electron microscope images of the surfaces loaded with Aspergillus spp. and Cladosporium spp. and then treated with aqueous suspension of wollastonite.
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Minerals 13 01170 g008
Figure 8. Powder X-ray diffraction pattern of starting sample indicating mineral composition: Q—quartz; C—calcite.
Figure 8. Powder X-ray diffraction pattern of starting sample indicating mineral composition: Q—quartz; C—calcite.
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Minerals 13 01170 g009
Figure 9. Powder X-ray diffraction patterns treated with aqueous suspension of wollastonite: Q—quartz; C—calcite; W—wollastonite.
Figure 9. Powder X-ray diffraction patterns treated with aqueous suspension of wollastonite: Q—quartz; C—calcite; W—wollastonite.
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Minerals 13 01170 g010
Figure 10. (a) Segmented SEM image for the sample with inoculated Aspergillus spp.; (b) segmented SEM image for the sample with Aspergillus spp. inoculated after applying the aqueous suspension of wollastonite.
Figure 10. (a) Segmented SEM image for the sample with inoculated Aspergillus spp.; (b) segmented SEM image for the sample with Aspergillus spp. inoculated after applying the aqueous suspension of wollastonite.
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Minerals 13 01170 g011
Figure 11. (a) Segmented SEM image for the sample with inoculated Cladosporium spp.; (b) segmented SEM image for the sample with Cladosporium spp. inoculated after applying nano-wollastonite.
Figure 11. (a) Segmented SEM image for the sample with inoculated Cladosporium spp.; (b) segmented SEM image for the sample with Cladosporium spp. inoculated after applying nano-wollastonite.
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Table 2. Weight of rock samples before and after applying aqueous suspension of wollastonite and 48 h after applying it, respectively, after drying.
Table 2. Weight of rock samples before and after applying aqueous suspension of wollastonite and 48 h after applying it, respectively, after drying.
Weight (g)InitialAfter Wetting
(Distilled Water) (Day 1)		After Fungal Inoculation
(Day 1)		Before Applying Aqueous Suspension of Wollastonite
(Day 4)		After Applying Nano
Aqueous Suspension of Wollastonite (Damp)
(Day 4)		After Gel Dried
(48 h Post-Application)
(Day 6)		Size
L × W × H (mm)
Milestone R19.34-----23/22/7
Milestone R28.42-----22/21/6
Sample 1
A		6.696.816.826.957.01
(+ 0.06 g gel)		6.9720/20/5
Sample 2
E		7.447.657.707.707.84
(+ 0.14 g gel)		7.6621/20/5
Table 3. Composition of aqueous suspension of wollastonite (after Taghiyari et al. [46,47]).
Table 3. Composition of aqueous suspension of wollastonite (after Taghiyari et al. [46,47]).
ComponentProportion (%w/w)
SiO246.96
CaO39.77
Water4.67
Al2O33.95
Fe2O32.79
MgO1.39
TiO20.22
Na2O0.16
SO30.05
K2O0.04
Table 5. The percentage of the surfaces occupied by Aspergillus spp. and Cladosporium spp. before and after applying the aqueous suspension of wollastonite.
Table 5. The percentage of the surfaces occupied by Aspergillus spp. and Cladosporium spp. before and after applying the aqueous suspension of wollastonite.
SampleClassPixel CountPercent (%)Total Pixel Count
Aspergillus spp.Aspergillus679,99559.331,145,984
Minerals465,98940.67
Aspergillus spp. aqueous suspension of wollastoniteAspergillus25,6142.231,145,984
Minerals111,0569.69
Aqueous suspension of wollastonite1,009,31488.08
Cladosporium spp.Cladosporium420,19836.671,145,984
Class 2 (background)44,8603.91
Class 3 (minerals)36,9173.22
Class 4 (minerals)644,00956.2
Cladosporium spp. aqueous suspension of wollastoniteCladosporium28010.251,145,984
Class 2 (fractures and minerals)160,96614.04
Aqueous suspension of wollastonite982,21785.71
Table 6. Results for accuracy measures used. R—recall; P—precision; CCI—correctly classified instances; k—kappa coefficient; PA—producer accuracy; UA—user accuracy; OA—overall accuracy.
Table 6. Results for accuracy measures used. R—recall; P—precision; CCI—correctly classified instances; k—kappa coefficient; PA—producer accuracy; UA—user accuracy; OA—overall accuracy.
 Accuracy Measures from WEKAAccuracy Measures from ENVI
SampleClassR
(%)		P
(%)		CCI
(%)		kPA
(%)		UA
(%)		OA (%)k
Aspergillus spp.Aspergillus99.597.998.20.9698.2769.9889.50.74
Minerals95.898.986.7799.38
Aspergillus spp. aqueous suspension of wollastoniteAspergillus98.871.798.90.9492.8476.4498.50.92
Minerals99.710099.6193.15
Aqueous suspension of wollastonite10098.998.5799.78
Cladosporium spp.Cladosporium95.69394.50.9194.9285.1687.20.79
Class 2 (background)99.899.8100100
Class 3 (minerals)87.796.482.7184.11
Class 4 (minerals)95.795.275.6292.23
Cladosporium spp. aqueous suspension of wollastoniteCladosporium65.982.898.60.9674.2794.1197.10.94
Minerals and fractures98.296.994.6999.8
Aqueous suspension of wollastonite99.199.399.995.63
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Ilies, D.C.; Blaga, L.; Ilies, A.; Pereș, A.C.; Caciora, T.; Hassan, T.H.; Hodor, N.; Turza, A.; Taghiyari, H.R.; Barbu-Tudoran, L.; et al. Green Biocidal Nanotechnology Use for Urban Stone-Built Heritage—Case Study from Oradea, Romania. Minerals 2023, 13, 1170. https://doi.org/10.3390/min13091170

AMA Style

Ilies DC, Blaga L, Ilies A, Pereș AC, Caciora T, Hassan TH, Hodor N, Turza A, Taghiyari HR, Barbu-Tudoran L, et al. Green Biocidal Nanotechnology Use for Urban Stone-Built Heritage—Case Study from Oradea, Romania. Minerals. 2023; 13(9):1170. https://doi.org/10.3390/min13091170

Chicago/Turabian Style

Ilies, Dorina Camelia, Lucian Blaga, Alexandru Ilies, Ana Cornelia Pereș, Tudor Caciora, Thowayeb H. Hassan, Nicolaie Hodor, Alexandru Turza, Hamid R. Taghiyari, Lucian Barbu-Tudoran, and et al. 2023. "Green Biocidal Nanotechnology Use for Urban Stone-Built Heritage—Case Study from Oradea, Romania" Minerals 13, no. 9: 1170. https://doi.org/10.3390/min13091170

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