Marble Surface Research Articles

Marble-Looking Fired Clay Tiles Produced by Utilizing Local Clay and Glass Cullet

This research is aim at developing marble-looking fired clay tile by utilizing waste glass cullet (CGC) mixed up with local plastic clay, sediment soil, and laterite clay. Boric oxide is also used as sintering aid. The experimental formulation is divided into 3 groups (A, B, and C) with 27 formulas. Test samples are moulded at 100 bar by Uni-axial pressing in dimension 50 x 100 x 7 mm and fried at temperature 850 °C. The initial results show that all formulas can develop marble texture and achieve Thai Industrial Standard TIS 2508-2555. Reducing firing temperature to 800 °C is the further investigation. However, formulas consisting 90% glass cullet are not selected, due to difficulty of molding workpieces. The final results of firing 800o C show that formula A6 containing 15% Plastic clay, 85% glass cullet, 2% boric oxide has the highest bending strength and lowest water absorption (<1%). Its properties are similar to formula C6 containing 15% laterite soil 85% glass cullet, 2% boric oxide. They can pass Thai Industrial Standard TIS 2508-2555 Floor Tiles BIb. Analyzing microstructure the fired specimens of these formulas by Scanning Electron Microscope has found glassy phases and dense matrix structures. Furthermore, Nepheline, Quartz, Cristobalite, Wollastonite, Devitrite, and Albite are identified by X-Ray Diffractometer. It can be summarized that marble texture surface fired clay tile can be developed by utilizing waste glass and low cost local materials.

The Chemistry of Chelation for Built Heritage Cleaning: The Removal of Copper and Iron Stains.

Chelators are widely used in conservation treatments to remove metal stains from marble, travertine, and limestone surfaces. In the current review the chemical aspects underlying the use of chelators for the removal of copper and iron stains from built heritage are described and clear criteria for the selection of the most efficient stain removal treatment are given. The main chelator structural features are outlined and the operating conditions for effective metal stain removal (pH, time of application, etc.) discussed, with a particular emphasis on the ability to form stable metal complexes, the high selectivity towards the metal that should be removed, and the high sustainability for the environment. Dense matrices often host chelators for higher effectiveness, and further research is required to clarify their role in the cleaning process. Then, relevant case studies of copper and iron stain removal are discussed. On these bases, the most effective chelators for copper and stain removal are indicated, providing chemists and conservation scientists with scientific support for conservation operations on stone works of art and opening the way to the synthesis of new chelators.

Rheological properties of high-performance SCC using recycled marble powder

Due to the impacts of cement manufacturing and depletion of the natural aggregates for concrete production, recycling of construction and demolition waste materials has become an alternative replacement to natural materials that lower their consumption and satisfy the environment. One of these alternatives is replacing cement with recycled materials from marble, ceramic, granite, and concrete wastes or even replacing the coarse aggregate with crushed marble and other stone wastes. Marble, granite, and natural stone wastes rapidly increase each year due to unmanaged waste disposal processes and the incremental increase in construction potential. Marble slurry, which comes from washing and cleaning marble surfaces, shows a filler effect by giving the concrete a denser and homogenous structure. This study evaluates the marble filler effects on the rheology in the fresh state of self-compacting concrete (SCC) through four SCC mixes by incorporating 10% marble powder (MP) and 33% fly ash (FA) as a partial ordinary Portland cement (OPC) replacement. Tests on paste and mortar were conducted to assess the suitability of the marble dosage on the water content and the superplasticizer amount. Spread flow and V-funnel tests were assessed. The results showed that mixes with MP required additional mixing water to ensure the same workability. Regardless of the high viscosity and air content, the overall developed marble SCC mixes reduced the cement quantity by up to 11% and provided excellent rheological properties like that of the reference mix. Besides the economic benefits, this transformation of waste to valuable materials involves environmental advantages and sustainability promotion.

Removal of Amoxicillin Drug from Aqueous Solution by using Marble Powder Surface Activated by Several Acids

In recent years, the problem of the removal drug from wastewater has become one of the most important global problems due to the accumulation of large quantities of drugs on the surface of the water, which causes a lack of penetration of sunlight into water contaminated with drug, and this leads to a reduction in aquatic life forms for all living organisms and also leads to problems large environmental impacts and many dangerous diseases for humans. An attempt was made to prepare an environmentally friendly, economical and available surface that has a high absorption capacity to remove the contaminants of pharmaceuticals such as amoxicillin (AMX) drug. In this study, waste material such as white marble was used as an absorbent material, and its adsorption properties were enhanced and activated by treating it with several acids (HCL, H2SO4, and HNO3). The prepared white marble before and after adsorption were characterized by field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). The influence of several parameters like contact time (5–120 minutes), initial concentration of drug (10–50 mg/L), adsorbent dosage (0.02–0.2 g), solution temperature (10–40oC), and pH (2–10) was estimated for adsorption method optimization. The equilibrium adsorption result was examined utilizing the isotherm Langmuir, and isotherm Freundlich models. The attained data indicated that, sorption was found to be fast, 84.44% within 1 hour.

Recolonization dynamics of marble monuments after cleaning treatments: A nine-year follow-up study

The prevention and control of biological patinas on outdoor stone monuments represent a demanding challenge for the conservation of cultural heritage also due to some microorganisms, particularly resistant to treatments, such as black meristematic fungi, an eco-physiological group well known for its tolerance to extreme conditions. Even if several methods and eco-friendly products have been proposed as new alternatives, traditional biocides are still far from being completely replaced. Recolonization is a natural process that occurs sooner or later after cleaning. The time that elapses until its occurrence can vary considerably depending on environmental conditions and the used products; unfortunately, the papers describing the effect of treatments over time are rare. This work aims to shed light on the recolonization process of marble surfaces in the ancient monumental cemetery of Bonaria (Cagliari) after nine years from treatments, evaluating the long-term efficiency of two different cleaning methods, namely dimethyl sulfoxide-based gel (DMSO-based gel) and Biotin T (a didecyldimethylammonium chloride-based product-). In this context, the microflora present before treatments and in the following years was assessed by culture-based methods and identified by molecular techniques, with attention on black meristematic fungi, which were used as reference for the most resistant lithobiontic organisms. Different environmental parameters, such as temperature, exposition, dominant winds, and rainfall, were considered, and infrared thermography, portable light microscopy, and image analysis were used. This research evidenced the influence of water availability and lightning in recolonization processes, the transition from the pioneer fungal community versus more resistant black fungal species after Biotin T treatment, and the long-lasting efficiency of the DMSO-based gel. These findings prove that this low-impact method deserves more attention in the conservation of outdoor marble monuments, emphasizing the importance of long-term studies.

Looking for Novel Natural Gels to Improve Cleaning Methods for Bronze Leachates on Marble.

Marble is one of the materials most susceptible to copper leaching, resulting in easily identifiable turquoise stains on the marble. This problem is particularly relevant when we are talking about marble structures of heritage value. For this reason, conservators look for cleaning materials that are specific to the structure to be treated without damaging the original surface. Materials such as agar have been studied for a long time. Agar creates a controlled water release system that adapts to the needs of conservators who seek the greatest possible cleanliness without damaging the material to be treated. To improve the cleaning, chelating agents such as EDTA are added to the agar composition. However, the microbiological growth and the damage it produces to the original material are disadvantages to take into account. In order to solve these problems, other natural materials with cleaning potential such as kudzu and konjac gels were studied in combination with other chelating agents such as citrate, oxalate, and gluconic acid. For the characterization and evaluation of copper cleaning, various analytical techniques were used, including Raman spectroscopy, colorimetry, X-ray fluorescence (XRF), and inductively coupled plasma mass spectrometry (ICP-MS). In this study, both konjac and kudzu emerged as promising alternatives to agar, revealing distinctive features such as simplified preparation methods and inherent antimicrobial properties. The EDTA chelator was found to be the most harmful for marble surfaces, as it extracted a greater amount of calcium from the marble during application of the gels doped with it. Citrate and gluconic acid have been identified as a promising substitute to prepare doped gels for the removal of copper stains. These compounds exhibit comparable or potentially superior cleaning capabilities than EDTA, with no negative side effects.

Advancing Inorganic Microcapsule Fabrication through Frozen-Assisted Interfacial Reactions Utilizing Liquid Marbles.

Inorganic microcapsules (IMs) have gained significant attention as versatile platforms for delivering functional agents in various fields. Traditional template-dependent methods employing hard templates often involve complex and harsh template removal processes. Achieving IMs with diverse composition and structure remains challenging with current preparation strategies. Therefore, in this work, we have for the first time demonstrated an extremely facile and efficient liquid-marbles-based template approach for fabricating pure inorganic microcapsules via interfacial reaction in a mild aqueous solution. The water-water reaction interface is created by changing the wettability of the liquid marble (LM) surface through the icing-melting process. The composition and function of the inorganic shell could be easily adjusted by varying the inorganic reagent species of the interfacial reaction, the hydrophobic particle of the shell, and the reaction environment according to the specific requirements of the application field. Such an approach provides a flexible platform for material preparation.

The movement pattern of particles on the surface of liquid marble during rupture based on the DIC algorithm

The stability of liquid marbles is critical to their application in sensors, microfluidic control, microreactors, and other fields. A more comprehensive understanding of the rupture kinetics of liquid marble is instructive for studies in improving the stability of liquid marble. However, the mechanism of rupture of liquid marbles is not clear at present, therefore, this paper addressed this issue by calculating the displacement of particles on the surface of a liquid marble using the DIC (Digital Image Correlation) algorithm. The distribution characteristics of the particles on the surface of the liquid marble and their movement patterns were clarified, the causes of cracks on the marble surface were analyzed, the mechanism of liquid marble rupture was derived, and the effect of volume on rupture kinetics was analyzed. Based on the obtained data, a method was proposed to control the maximum compression that the liquid marble can withstand by spraying different sizes of superhydrophobic coatings. This paper contributes to the study of the stability of liquid marble, allowing its wider application in industrial production.

Centimetric circular areas uncolonized by microbial biofilms (CUMBs) on marble surfaces and insights on a lichen-related origin

This study investigated the poorly known phenomenon of Centimetric circular areas Uncolonized by Microbial Biofilms (CUMBs) which is frequently observed on natural and heritage stone surfaces displaying widespread lithobiontic colonization. In order to unveil a possible relationship with past lichen colonization, analyses were carried out on the distribution, morphometry, physical and mineralogical properties, and microscopic features of CUMBs on the marble surfaces of a balustrade in the Garden of a Savoy residence in Torino (Italy; UNESCO-WHS 823bis) and in its original quarry site in the W-Alps. Image analyses of CUMBs displayed a distributional and dimensional compatibility with lichen thalli (re-)colonizing surfaces in their vicinity. Invasive analyses on quarry materials displayed similar microscopic modifications in marble layers beneath CUMBs and lichens, associated to a higher stabilization of the calcite {01–12} form, which is favoured by the presence of organic substances. These findings support the hypothesis of a lichen origin for some CUMBs, which may derive from the modification of physical stone properties and/or a long-lasting allelopathic effect affecting surface bioreceptivity.

How APTMS Acts as a Bridge to Enhance the Compatibility of the Interface between the Hydrophilic Poly(vinyl alcohol) Film and the Hydrophobic Stearic Acid Coating.

The hydrophobic modification of poly(vinyl alcohol) (PVA) film as a biodegradable packaging material has received significant attention in recent research. Despite the use of stearic acid (SA) as a coating for the PVA film, a challenge persists due to the poor compatibility between SA and PVA. This study addressed the aforementioned issue by utilizing (3-aminopropyl)trimethoxysilane (APTMS) as a bridging agent to establish a connection between the hydrophilic PVA film and the hydrophobic SA coating through hydrogen bonding and chemical reactions. First, SEM and EDS analyses confirmed the enhanced interfacial compatibility between the SA coating and the PVA film. Subsequently, the results from 1H NMR, FTIR, and XPS experiments presented evidence of hydrogen bonding and chemical reactions among APTMS, SA, and the PVA film. Interestingly, the PVA-APTMS-SA film demonstrated a contact angle of 120.77°, a water absorption of 7.81%, and a water vapor transmission rate of 8.69 g/m2/h. Furthermore, such a composite film displayed exceptional adhesion performance, requiring detachment stresses of 9.86 ± 0.91 and 6.17 ± 0.75 MPa when tested on glass and marble surfaces, respectively. In conclusion, the PVA-APTMS-SA film exhibited significant potential in extending the freshness of fresh-cut apples, making it a promising eco-friendly packaging material for food preservation.

Discontinuity Detection System in Marble: Analysis of the Time-Frequency Characteristics of Ultrasonic P-waves

Abstract This study attempted to determine both the presence and the appearance of the surface of a crack artificially created in a marble block without axial loading or compression by FFT analysis of ultrasonic longitudinal sound waves by scanning the surface. In such respect, the study differs from other studies in the literature. The aim of the study was to minimize marble waste by determining the most appropriate slab cut direction based on the orientation of the fracture or discontinuity within the marble block. During location-controlled scanning of the marble surface, mean longitudinal wave velocity, Young modulus, Poisson ratio and longitudinal wave velocity variation data were obtained using a V-Meter Mark IV™ ultrasonic test device. For each location, longitudinal ultrasonic velocity data was taken at 250 kHz sampling rate and 256 data points were created. Data from the computer environment were subsequently reorganized using the MATLAB software and FFT conversions for such velocity data were obtained for each location. Then, the peaks of the FFT transformation components were determined by using the “Findpeaks” function in MATLAB‘s signal processing toolbox. The number of peaks in the 50-60 kHz range was determined for each location. A single difference was determined between the peak numbers at the locations within the cracked and uncracked regions. By examining the FFT graphs, it was determined that such additional peak occurring in the cracked regions appeared as a second frequency component near the dominant frequency values. Points with secondary frequency were recorded as 1, while all other points were recorded as 0 in a new matrix. Such data matrices created for each sample were examined by visualization in the form of surface graphics. Using these graphics, the orientations of discontinuities within the marble block may be determined according to the scanning surface.

UV-Curable Fluorocarbon Polyurethane Coatings for Marble Kitchen Countertops

Marble kitchen countertops and other natural stone surfaces are often stained by various food ingredients and contaminants during daily use and require frequent cleaning, which is time-consuming and leads to the wasting of water. If the surface is coated with a hydrophobic and oleophobic coating, food ingredient contamination becomes easier to wipe clean. Therefore, a UV-curable monomer with fluorocarbon branched chains was synthesized and added to UV-curable coatings in different ratios. The preferred formulation that meets the basic performance requirements of UV-curable coatings, and has the best hydrophobic and oleophobic properties, was designed and selected. The formulation was upgraded by adding a hydrofluoric ether (HFE) solvent. These upgraded formulations were tested for hydrophobicity and oleophobicity under various conditions. The addition of an HFE solvent improves the initial water and cetane contact angles of the paint film, as well as the water and cetane contact angles under various conditions. Moreover, the upgraded formulations have better stain resistance. The degree of hydrophobicity and oleophobicity improvement is positively correlated with the addition of an HFE solvent. The UV-curable fluorocarbon polyurethane coating has good adhesion on a marble surface that has been polished and primed. Due to the presence of TEOH-6 instead of PFOA, the low content of fluorocarbon functional groups effectively located on the film surface makes the coating quite stable and safe.

Laser cleaning of paint layers on white marble surface based on cooperative use of laser-induced breakdown spectroscopy and image binarization

The key to precisely removing paint layers sprayed onto stone surfaces using laser cleaning without damaging the stone substrate is to select the optimized laser parameters based on the online monitoring methods. In this paper, a pulsed laser beam with a high-pulse repetition frequency of 100 kHz, a pulse width of 200 ns, and a wavelength of 1064 nm was used to clean 39 µm- and 31 µm- thick of gold and silver paint layers off of white marble surfaces. The optimized average laser power for removing the paint layers was determined to be 40 W using laser-induced breakdown spectroscopy (LIBS) method and an image binarization method. Under the optimized average laser power of 40 W, the optimized spot overlap ratios for cleaning the layers of gold and silver paint were determined to be 10% and 30% respectively, using the image binarization method. The corresponding optimized number of cleaning shots was 5 and 4, respectively. The laser cleaning efficiency for both the gold and silver paint layers exceeded 95%. It was thereby demonstrated that this research protocol based on the cooperative use of two online monitoring methods to determine the optimized laser parameters in sequence (average laser power → spot overlap ratio → number of cleaning shots) not only optimizes the laser cleaning efficiency for different paint layers but does so without causing any damage to the white marble substrate.

Benefits of using nonionic saccharide surfactant‐based detergents for nanostructured fluids as stubborn graffiti paint remover

AbstractExamples of nanostructured fluids (NSFs) used as highly specialized “brush‐on, wipe‐off” detergents for the removal of graffiti coatings resistant to removal are water‐in‐oil nanoemulsions that have been stabilized with nonionic saccharide surfactants. Nanodetergents with safe, ecofriendly ingredients were produced using high‐pressure homogenization (HPH). These ingredients included D‐limonene or 3‐methoxy‐3‐methyl‐1‐butanol, esterified vegetable oils, and alkyl polyglucosides (APG). Responsive surface methodology (RSM) optimization was used to identify the most efficient detergents for removing stubborn graffiti coatings. Two different types of black paint containing nitrocellulose or bitumen as components to strengthen the paint properties were used to create a stubborn graffiti coating on a marble surface. The effectiveness of the nanodetergents in removing the stubborn graffiti coatings was evaluated, and the results revealed a considerable variation in the pace at which the coatings could be removed by the nanodetergents, despite the fact that both paints strengthened with different additives showed similar surface properties. It was found that alkyl polyglucosides are highly efficient in stabilizing water‐in‐oil nanoemulsion systems, including diverse solvent types. These nanoemulsions can be used as specialized “brush‐on, wipe‐off” detergents for the precise removal of different graffiti coatings, which require a specified action period to prevent destroying the underlying original substrate.

Characterization of ablation conditions with the grayscale representation for Nd:YAG laser to decolor the blue‐ink on marble stone surface: Decoloration dependency on the laser flux power, wavelength, and the water spraying

AbstractAiming at artwork restoration application, to decolor the blue‐ink stained marble stone surface was studied for finding out efficient ablation conditions with the use of Q‐switched Nd:YAG laser as the function of laser flux power, wavelength, and its water spray effect. The blue ink mostly consists of indigo dye which absorbs light in the visible region. The decoloration, or decolor efficiency, was evaluated by using the grayscale representation instead of the RGB method. Our experimental results show that the 532 and 355 nm wavelengths are more suitable for blue‐ink decoloration. No decoloration was observed at the 1,064 nm ablation, which is usually regarded as effective on black‐crust stained surfaces. The decolor effect of the water‐sprayed surface was found to be effective at the higher laser flux power. A photo‐absorption‐assisted laser ablation mechanism is proposed in addition to the plasma‐assisted laser ablation mechanism.

Redox-stratified seawater during the GOE: Evidences from rare earth elemental and C-O isotopic compositions of Paleoproterozoic BIF and carbonate rocks from the Taihua Group, North China Craton

The Paleoproterozoic Great Oxidation Event (GOE) is known for the dramatic change in atmospheric composition that led to oxygen becoming a persistent component of global surface processes. Drastic environmental changes greatly affected ocean and atmosphere chemistry. However, the distribution of dissolved oxygen in the ocean during the GOE is still unclear as rare contemporary sediment-records have been found. In order to identify the redox state of both shallow and deep water, and reveal the ocean redox structure during this time, we present new major and trace elemental and C-O isotopic data of bulk samples of the banded iron formation (BIF), dolomitic marble, and graphite-bearing marble of the early Paleoproterozoic upper Taihua Group in the Lushan area, southern margin of the North China Craton (NCC). The BIF samples exhibit typical major and trace element characteristics akin to very pure marine chemical sediments, such as the shale-normalized positive La, Ga, and Y anomalies, indicative of a marine depositional setting. In these BIF samples, both negative Ce anomalies and the lack of Ce anomalies reflect the presence of both oxic and suboxic/anoxic water in the ocean. Samples of the dolomitic marble are characterized by extremely low amounts of crustal material (such as Al, Ti, Zr, Hf) and high Y/Ho ratios (46–66), also implying a pure marine chemical origin. Excluding some contaminated samples, the rest of the graphite-bearing marble samples display similar features of the dolomitic marble. Significant positive Ce anomalies and high light to heavy REE (Pr/Yb(SN)) ratios in both dolomitic marble and graphite-bearing marble are essentially consistent with the 2.2–2.1 Ga carbonates from the Guanmenshan Formation of the Liaohe Group in the NE Sino-Korean Craton. Combined with the Ce anomalies in the BIF samples, we consider that the seawater when the upper Taihua Group deposited was redox-stratified from oxic shallow water to deeper anoxic water. Besides, the graphite-bearing marble record coeval surface water in the column that was enriched in nutritive materials and beneficial to microbiology and high productivity. Moreover, the early Paleoproterozoic IFs in the Songshan Group and the Lüliang Group in the NCC also exhibit significant both positive and negative Ce anomalies and enrichment of redox sensitive elements. These evidences, therefore, suggest that redox-stratified seawater occurred extensively during the GOE.

Analytical Investigation of Iron-Based Stains on Carbonate Stones: Rust Formation, Diffusion Mechanisms, and Speciation

In cultural heritage, unaesthetic stains on carbonate stones due to their close contacts with metals are of concern for the preservation of sculptures, monumental facades and archeological finds of various origin and antiquities. Rust stains made up of various oxidized iron compounds are the most frequent forms of alteration. The presence of ferric iron on rust-stained marble surfaces was confirmed in previous studies and oriented the choice of the best cleaning method (based on complexing agents specific for ferric ions). However, the composition of rust stains may vary along their extension. As the corrosion of the metallic iron proceeds, if the oxygen levels in the surroundings are low and there are no conditions to favor the oxidation, ferrous ions can also diffuse within the carbonate structure and form a variety of intermediate compounds. In this study, the iron stains on archeological marbles were compared with those artificially produced on Carrara marbles and Travertine samples. The use of integrated techniques (optical and scanning electron microscopy as well as Mössbauer and XPS spectroscopy) with complementary analytical depths, has provided the overall information. Rust formation and diffusion mechanisms in carbonates were revealed together with the evolution of iron speciation and identification of phases such as ferrihydrite, goethite, maghemite, nanomagnetite, and hematite.

Non-Invasive SWIR Monitoring of White Marble Surface of the Cathedral of Santa Maria del Fiore (Florence, Italy)

The monitoring of stone alteration represents a key factor in the knowledge and prediction of the status of conservation of building stones in the urban framework. A continuous monitoring requires a non-destructive analytical approach and, possibly, a simple, low-cost and effective tool to study the decay processes. Previous studies demonstrated the capability of the SWIR hyperspectral technique to gain information on the degree of sulfation of carbonate stone surfaces. In this study we aim at setting up a protocol to investigate on-site the sulfation degree of the white marble cladding surfaces of the worldwide-famous Santa Maria del Fiore Cathedral in Florence (Italy). The proposed protocol couples information by SWIR hyperspectral and colorimetric techniques. We have proved that, in selected areas investigated at a distance of nine years, the colour and the mineralogical changes (i.e., sulfation) are significantly greater than the relative uncertainties of the two methods. Moreover, the proposed protocol results rapid, repeatable and fully not invasive.

Carbonate and Oxalate Crystallization Effected by the Metabolism of Fungi and Bacteria in Various Trophic Conditions: The Case of Penicillium chrysogenum and Penicillium chrysogenum with Bacillus subtilis

The present work contributed to the patterns of crystallization affected by the metabolism of fungi and bacteria in various trophic conditions and specifically covers the case of Penicillium chrysogenum and P. chrysogenum with Bacillus subtilis. The cultivation of microorganisms was carried out on the dolomitic calcite marble in liquid Czapek–Dox nutrient medium with glucose concentrations of 1, 10 and 30 g/L. The study of the crystal component of mycelium formed on the marble surface was supported through powder X-ray diffraction, scanning electron microscopy and energy-dispersive X-ray spectroscopy; the quantitative content of the extracellular polymer substance (EPS) and low-molecular-weight organic acids (LMWOAs) in the medium was determined through chromatography–mass spectrometry (GC-MS). The results obtained clearly demonstrated the unique ability of the fungus P. chrysogenum to not only release organic acids (primarily oxalic), but the EPS also which significantly affected the pH of the culture liquid and, accordingly, the carbonate and oxalate crystallization. Carbonate crystallization manifested in the presence of Bacillus subtilis as well. The transition from oxalate crystallization to carbonate and vice versa could occur with a change in the species composition of the microbial community as well as with a change in the nutritional value medium. Under the conditions closest to natural conditions (glucose content of 1 g/L), through the action of P. chrysogenum, oxalate crystallization occurred, and through the action of P. chrysogenum with B. subtilis, carbonate crystallization was observed. The identified patterns can be used to reveal the role of fungi and bacteria in the oxalate–carbonate pathway.

Will to the Original: Platonism in Henry James’ Roderick Hudson

Will to the Original: Platonism in Henry James’ <i>Roderick Hudson</i>