Polarized Light Microscopy Observations Research Articles

The frieze of the Art of War in the Ducal Palace of Urbino: conservation issues, materials, and executive techniques

The frieze of the Art of War was originally positioned along the sides of the facade of the Ducal Palace in Urbino (Marche, Italy), and it is currently located in the palace’s Chancellery Room. The frieze, probably elaborated by Federico da Montefeltro around 1474, consists s of stone bas-reliefs illustrating a rich iconographic repertoire depicting numerous engineering machines and symbols related to the military and political spheres. The present work aims to deepen the knowledge of the Art War frieze and to clarify some doubts regarding the original shape of the bas-reliefs, the constituent material, and the executive technique; conservation issues were also considered. Polarized light microscopy observations were carried out on the stone materials, identifying the use of a packstone referable to the Calcare Massiccio A Formation (Hettangian-Lower Pliensbachian p.p.). This stone, locally known as Piobbico Travertine, was excavated in the Val d’Abisso quarries, part of the Umbria-Marche ridge. Ca-oxalates were detected by Fourier transform infrared analysis in the brownish patinas that mainly cover the surfaces of the bas-reliefs; they could be related to ancient conservation treatments and/or to biological agents. Regarding the execution technique, a thorough autoptic examination allowed for a better understanding of the original conformation of the bas-reliefs and the carving process. Stylistic and executive differences in the execution of the same detail were observed in different bas-reliefs, confirming the activity of various sculptors. Different decay typologies were used to consider the debate regarding the original arrangement of the frieze on the facade, validating the most accredited hypothesis.

Artificial deterioration of vegetable-tanned leather under synergistic effect of temperature and humidity

• The synergistic effect of temperature and relative humidity on the deterioration of mimosa-tanned leather was investigated. • The changes in structure and thermal properties of artificially aged mimosa-tanned leather were systematically studied. • The TG-FTIR technique was employed to analyze the deterioration with the evolved gaseous products during thermal degradation. The deterioration of mimosa-tanned leather artificially aged at 80 °C and 60% relative humidity (RH) for up to 32 days was investigated. The changes in thermal properties, morphology, and structure were analyzed by thermogravimetric analyzer (TGA), polarized light microscopy (PLM), scanning electron microscopy (SEM), attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), and X-ray diffraction (XRD). The results showed that the mimosa-tanned leather was deteriorated with a decrease in hydroxyproline content. After the artificial aging treatment, the thermal resistance of the mimosa-tanned leather was reduced. This result was further confirmed by PLM observations that the shrinkage temperature of the collagen fibers decreased with increasing aging time. The evolved gaseous products from the TGA were detected by TGA-FTIR to characterize the deterioration caused by aging. After aging, the evolution yield of nitrogen-containing products such as NH 3 , HNCO, and pyrrole decreased, while the evolution yield of CO 2 increased. According to the ATR-FTIR, XRD, and SEM results, the orientation and structural integrity of the collagen fibers were destroyed by artificial aging.

Growth, Structure, and characterization of new High-TC Piezo-/Ferroelectric Bi(Zn2/3Ta1/3)O3-PbTiO3 single crystals

In this work, new bismuth-based complex perovskite piezo-/ferroelectric single crystals of the (1-x)PbTiO3-xBi(Zn2/3Ta1/3)O3 solid solution have been successfully grown by the high temperature solution method (HTSG). The crystal structure was found to be tetragonal at room temperature by means of structural analysis by X-ray diffraction and domain examination by polarized light microscopy (PLM). High Curie temperature (TC = 470 °C) was determined by dielectric measurements and PLM observations. Band-like domain structures were observed in the (001)-oriented single crystal with a width of 100–200 µm. Good piezoelectric performance (d33 = 251 pC/N) and high coercive field (EC = 30 kV/cm) were found by the piezoelectric and ferroelectric characterizations. Detailed crystal structural refinement was performed to establish the structure–property relationship in this system. Comparative studies of current bismuth-based complex perovskite solid solution single crystals point to the advantages of the Bi(Zn2/3Ta1/3)O3-PbTiO3 single crystals in terms of high TC, good piezoelectric performance, and high coercive field. These advantages make this piezo-crystal system a favourable candidate for potential high-temperature and high-power electromechanical applications.

Relating reactivity to structure in cokes and carbon materials: Temperature-programmed oxidation and microscopy techniques

A series of carbon materials and composites has been characterized by temperature-programmed oxidation (TPO), polarized light microscopy (PLM), scanning electron microscopy with energy dispersive X-ray spectroscopy (EDS), and temperature-programmed desorption coupled with mass-spectrometry analysis. For materials containing anisotropic carbons, a consistent relationship was found between oxidation reactivity and optical texture. Polarized-light microscopy in combination with TPO can help assessing the relationships between oxidation reactivity and optical texture of anisotropic carbons. Deconvolution of TPO profiles and PLM observations can effectively identify the individual components of multi-component carbon materials with important implications in structure-property relationships and their applications. For amorphous carbons with isotropic optical textures, TPO profiles were found to be influenced by the surface chemistry of the materials. It appears that the TPO technique under controlled conditions provides a rapid analysis of solids carbons with respect to their structure and properties. This is particularly useful for the analysis of carbon composites with multiple phases in combination with microscopic examination and elemental analysis using EDS.

A mineralogical and geochemical investigation of modern aeolian sands near Tonopah, Nevada: Sources and environmental implications

The mineralogical and geochemical composition of sands across arid to semi-arid landscapes can be used to evaluate the nature of their source lithologies. Once these characteristics are established, these sands have the potential to be implemented as background reference materials in environmentally-focused studies (e.g., mine waste pollution). Tonopah, Nevada is an economically disadvantaged town with a long history of silver mining. Tonopah and surrounding areas with similar histories are also examples of significantly understudied regions with respect to several environmental concerns.Sands sampled in this study are part of a star-shaped dune system ~15 km north of Tonopah. They are medium-grained and are very well sorted: arithmetic mean grain size from 263 to 335 µm. From Quartz – Feldspar – Lithic (QFL) classification the sands are feldspathic litharenites to weakly litharenitic. Powder X-ray diffraction and polarized light microscopy observations identify quartz, ordered calcian albite, and sanidine as the dominant minerals with rarer calcite, magnesian calcite, and amphibole. Scanning electron microscopy indicates grains have a range of textural maturity, with rhyolitic and basaltic lithic grains present. From bulk elemental chemistry, sands are geochemically akin to that of Earth’s bulk upper continental crust, are quartz-rich, formed in arid to semi-arid climates, and were derived from a felsic igneous province (or provinces).The origin of these sands is further investigated by comparing bulk major elemental signatures to the composition of global, regional, and local dune systems, in addition to local and regional bedrock. Regionally, Tonopah sands are compositionally similar to those of the Mojave Desert dune fields (e.g. Cadiz) and distinct from those of the Algodones and Parker dunes of California and Arizona respectively. Consistent with source inferences for the Cadiz, Danby, and Dale lake sands of the Mojave Desert, Tonopah sands are inferred to be derived from chemically evolved provinces. For Tonopah, derivation from the local, Micoene-aged, andesite-dacite-rhyolite suites is inferred.Through comprehensive characterization of the Tonopah sands a geogenic background composition for the region, and an important reference material for future environmental investigations, has been established.

Spectroscopic/Microscopic Elucidation for Chemical Changes During Acid Pretreatment on Arundo donax

The Arundo donax is a typical fast-growing species from the family Gramineae, which is widely cultivated in China. With a huge yield of A. donax in China, this plant offers great potential for biofuels production. The different types of organization of cell and the tissue in the A. donax could influence the efficiency of enzymatic hydrolysis. In this study, A. donax was subjected to 0.5% (w/w) sulfuric acid (H2SO4) for pretreatment at 140°C for 10 min, 20 min, 40 min, and 60 min, respectively. The changes in microstructure, chemical composition, topochemical properties were comprehensively analyzed. Using a series of spectroscopic and microscopic techniques including Fourier transform infrared spectroscopy (FT-IR), X-Ray diffraction (XRD), polarized light microscopy (PLM), and confocal Raman microscopy (CRM) to obtain the correlative structural and chemical information. Analysis results of chemical composition, FT-IR spectra and XRD indicated that with increasing reaction time, more hemicellulose and lignin would be removed. Correspondingly, there was an obvious increase of the cellulose relative crystallinity via extending reaction time. Results of the PLM observations showed that the birefringence gradually dimmed due to the diminishing of the cellulose component. Furthermore, the CRM mapping images showed the lignin component in compound middle lamellar (CML) was difficult to remove relatively as compared with that in secondary walls. These results indicated that the combination of spectroscopic and microscopic elucidation could give an insightful understanding of chemical changes in cellular level during pretreatment.

Solution-mediated phase transformation at particle surface during cocrystal dissolution

In this study, we investigated solution-mediated phase transformation (SMPT) during cocrystal particle dissolution. When the solubility of a cocrystal is higher than that of the free form, the concentration of the free form can be supersaturated at the dissolving cocrystal surface, as well as in the bulk phase. Therefore, SMPT may occur either in the bulk phase or at the particle surface (PS-SMPT). Carbamazepine - glutaric acid cocrystal (CBZ-GLA) was used as a model cocrystal. Dissolution tests were performed under a non-sink condition. The residual particles were analyzed by polarized light microscopy (PLM), scanning electron microscopy, powder X-ray diffraction, and differential scanning calorimetry. Solvent-shift bulk phase precipitation tests and real-time PLM observation of PS-SMPT were also performed. In the dissolution test, little or no supersaturation was observed. CBZ-GLA particles rapidly and completely transformed to aggregates of CBZ dihydrate (CBZ DH) (>95% within 3 min). The outer shape of the aggregates preserved that of initial CBZ-GLA particles, but distinctly differed from CBZ DH precipitated from the bulk phase. Real-time PLM observation revealed that PS-SMPT started within several seconds after contact with the medium. These results suggested that CBZ-GLA particles transformed to the aggregates of CBZ DH via PS-SMPT.

The formation of high-alumina clays in a pedosedimentary sequence of Marilia Formation (Western Minas Gerais, Brazil)

Mottled horizons and iron crusts are widespread in soil developed upslope on flat sedimentary plateau located in western of Minas Gerais State (Brazil). In the area, important deposits of high-alumina clays are located at lower topographic position suggesting a lateral transformation system from mottled horizons. External factors, generally linked to more humid climatic conditions, could explain the spatial variation of pedogenic materials in landscape. The objective of this paper is to discuss the genetic relation between the mottled and high-alumina clays horizons in a pedosedimentary sequence of Marilia Formation within the context of landscape evolution. Punctual observations using pits and auger were performed along typical soil transect. X-ray diffraction (XRD), X-ray fluorescence spectrometry (XRF), polarized light microscopy observation and scanning electron microscopy (SEM) were used to determine the affiliation between soil materials. Rietveld refinement was applied to quantify the mineralogical phases of the different layers. The results showed that both, mottled and high-alumina clays are a ferruginous depleted material, inherited from the iron crust dissolution. The horizons are aligned in the topography, despite the longer permanence of water table in depressed zones of the plateau which enhances iron dissolution and relative enrichment of gibbsite. The relative preservation of the iron crusts occurs in the altitude > 980 masl; below this level iron crusts disappear due to a generalized elevation of the groundwater in the flat plateau.

Changes in physicochemical and structural properties of tapioca starch after high speed jet degradation

Tapioca starch (TS) suspensions (10%, w/v) were subjected to high speed jet (HSJ) processing at 80, 120, 160, 200 and 240 MPa for one pass, and the effects of HSJ treatment on solubility, rheological, pasting, morphological and molecular properties were further investigated. Polarized light microscopy observation revealed TS was partly gelatinized, and the number and clarity of“Maltese cross” decreased with the increase of HSJ pressure. The solubility of TS was increased significantly from 1.59% (0 MPa) to 12.11% (240 MPa). Dynamic oscillation analysis showed that TS gels displayed less elastic and more liquid like after HJS treatment, and all samples displayed pseudo-plastic properties during flow properties analysis. Rapid Visco Analyser measurement indicated that treated samples showed significantly decreased in peak viscosity and exhibited a lower tendency towards retrogradation on cooling process compared to untreated TS. Size-exclusion chromatography analysis suggested that the degradation of TS happened during HSJ treatment, and the degradation was more prominent beyond 160 MPa. The results showed that the significant changed in physicochemical and structural properties of treated TS were related to its degradation. These observations would provide an alternative and environmentally approach for starch modification.

The quantitative assessment of coke morphology based on the Raman spectroscopic characterization of serial petroleum cokes

A series of petroleum coke species obtained from commercial plants has been studied by polarized-light microscopy observation (PMO), scanning electron microscope (SEM), and Raman spectroscopy characterization (RS). The morphological characteristics of needle coke, shot coke, and transition coke differed apparently from each other. An explicitly close Growth/Sigmoidal relationship between parameters determined from polarized-light micrographs and Raman spectra was observed. The full width at half maxima (FWHM) of D1350 was more appropriate than ID1350/IG1580 for morphological correlation, and then establishing the criterion. It was shown that RS with proper spectra decomposition procedure could be a suitable and convenient method to quantitatively assess the morphology of petroleum cokes.

Effect of monoglyceride content on the solubility and chemical stability of β-carotene in organogels

Organogels were prepared by structuring corn oil with monoglyceride (GMS), and the effect of GMS content on the properties of organogels and solubility and stability of β-carotene was evaluated. Organogels with different properties were obtained by changing the content of GMS (0, 10, 15, 20 and 25 g/100 g), and β-carotene of varied content (0, 5, 10, and 15 g/100 g) was incorporated. Polarized light microscopy observation and differential scanning calorimetry (DSC) analysis revealed that β-carotene at the concentration of 10 g/100 g did not form crystals in organogels, while it crystalized and precipitated in corn oil at the same concentration. Textural analysis and rheological measurement suggested that an increase in GMS content in the organogels resulted in the systems with higher gel strength. When organogels were exposed to UV light or stored at different temperatures, β-carotene presented higher retention ratios in the systems with higher GMS content. These findings suggested organogels have the potential to deliver higher loading of lipophilic bioactives with good stability.

Zona pellucida gene mRNA expression in human oocytes is related to oocyte maturity, zona inner layer retardance and fertilization competence.

Do the mRNA expression levels of zona pellucida (ZP) genes, ZP1, 2, 3 and 4 in oocyte and cumulus cells (CC) reveal relevant information on the oocyte? The ZP mRNA expression in human oocytes is related to oocyte maturity, zona inner layer (IL) retardance and fertilization capacity. ZP structure and birefringence provide useful information on oocyte cytoplasmic maturation, developmental competence for embryonic growth, blastocyst formation and pregnancy. In order to understand the molecular basis of morphological changes in the ZP, in the current study, the polarized light microscopy (PLM) approach was combined with analysis of the expression of the genes encoding ZP1, 2, 3 and 4, both in the oocytes and in the surrounding CC. This is a retrospective study comprising 98 supernumerary human cumulus oocyte complexes (COC) [80 Metaphase II (MII), 10 Metaphase I (MI) and 8 germinal vesicle (GV)] obtained from 39 patients (median age 33.4 years, range 22-42) after controlled ovarian stimulation. Single oocytes and their correspondingCC were analysed. Oocytes were examined usingPLM, and quantitative RT-PCR was performed for ZP1, 2, 3 and 4 in these individual oocytes and their CC. Ephrin-B2 (EFNB2) mRNA was measured in CC as a control. Presence of ZP3 protein in CC and oocytes was investigated using immunocytochemistry. Data were analysed using one-parametric and multivariate analysis and were corrected for the potential impact of patient and cycle characteristics. Oocytes contained ZP1/2/3 and 4 mRNA while in CC only ZP3 was quantifiable. Also ZP3 protein was detected in human CC. When comparing mature (MII) and immature oocytes (MI/GV) or their corresponding CC, ZP1/2 and 4 expression was lower in mature oocytes compared to the expression in immature oocytes (all P < 0.05) and ZP3 expression was lower in the CC of mature oocytes compared to the expression in CC of immature oocytes (P < 0.05). This coincided with a significantly smallerIL-ZP area and thickness in mature oocytes than in immature oocytes (all P < 0.05). In mature oocytes, IL-ZP retardance was significantly correlated with the expression of all four ZP mRNAs (all P < 0.05). The oocyte ZP3 expression was the main predictor of the fertilization capacity, next to IL-retardance and IL-thickness. Using stepwise regression analysis, IL-thickness combined with EFNB2 expression in CC and the patient's ovarian response resulted in a noninvasive oocyte fertilization prediction model. Not applicable. This is a retrospective study and the relation of oocyte mRNA levels to fertilization capacity is indirect as oocyte gene expression analysis required lysis of the oocyte. Overall relations between PLM observations, mRNA expression changes and intrinsic oocyte competence were successfully documented. As such PLM and CC gene expression are confirmed as valuable noninvasive techniques to evaluate oocyte competence. This study was funded by University of Torino, Italy, WFWG UZ-Brussel and Agentschap voor Innovatie door Wetenschap en Technologie IWT 110680, Belgium. All authors declare that their participation in the study did not involve actual or potential conflicts of interests.

Correlation of Temperature-Programmed Oxidation with Microscopy for Quantitative Morphological Characterization of Thermal Cokes Produced from Pilot and Commercial Delayed Cokers

A wide series of thermal cokes obtained from commercial delayed cokers and a pilot coking plant have been investigated by polarized light microscopy observation, scanning electron microscopy (SEM), and temperature-programmed oxidation (TPO) technology. For discrimination of the characterization of the coke samples, the anisotropy degrees of the cokes are found to be considerably different. According to the series of runs in the pilot plant, the restricted mesophase development in thermal cokes could be ascribed to the increasing severity of coking conditions. A previous proposed signal analysis procedure was then applied to the TPO profiles of the cokes to quantitatively acquire parameters for further correlation. A fairly good linear dependency of optical texture index (OTI) upon the proportion of anisotropic carbon species from TPO (correlation coefficient of 0.984) was observed. All of the results obtained in this and our previous (Chen, K.; Xue, Z.; Liu, H.; Guo, A.; Wang, Z. A temperature-programmed ...

High pressure induced gelatinization of red adzuki bean starch and its effects on starch physicochemical and structural properties

Red adzuki bean suspensions (20%, w/w) were subjected to high hydrostatic pressure (HHP) processing at 0.1, 150, 300, 450 and 600 MPa for 15 min, and the effects of this physical modification on the physicochemical and structural properties were investigated. Scanning electron microscope and polarized light microscopy observation revealed a complete starch gelatinization after treatment with 600 MPa. HHP–treated samples displayed weak diffraction peak intensity compared to native granules revealed by X-ray diffraction analysis. The light transmittance was found to significantly decrease after HHP treatment, while syneresis increased with increasing HHP pressures. The increases in the solubility of HHP–pressured granules are associated with crystalline structures destruction and increasing granule swelling power, respectively. The DSC analysis showed an increase in onset and peak temperature, and a decrease in conclusion temperature, gelatinization enthalpy and gelatinization temperature range. RVA results suggested that HHP changes pasting features, particularly when treated at 600 MPa, resulting in a considerable decrease in peak, viscosity, breakdown and final viscosity, and an increase in pasting temperature and peak time. The results have shown that the physicochemical changes of HHP–treated starch granules are based on the structural destruction of granules.

Study on the Inherent Factors Affecting the Modification Effect of EVA on Waxy Crude Oils and the Mechanism of Pour Point Depression

The Ar-Sai waxy crude oils were taken as the research objects, and the viscosity reduction rates and the condensation point reduction rates were regarded as the evaluation indexes, the impacts of components content of the crude oils and carbon number distribution of waxes on the modification effect of EVA-type pour point depressant (PPD) were analyzed by using gray correlation analysis method. The oil wax was acquired by applying the extraction and separation techniques initially, then the structures and the lattice parameters of wax crystals before and after adding the PPD were studied by polarized light microscopy observation and x-ray diffraction techniques, the mechanism of pour point depression was discussed at last. The results indicate that wax content and the low carbon number wax have significant influences on the modification effect of PPD, while the impact of high carbon number wax is relatively small. Co-crystallization is the main mechanism of pour point depression, nevertheless, the impacts of the asphaltenes, resins, solid particles, and light components of the crude oils on the modification effect of the PPD cannot be ignored.

Development of Chinese barium copper silicate pigments during the Qin Empire based on Raman and polarized light microscopy studies

Ancient Chinese objects dating from the Warring States period (475–221BC) to the Han dynasty (206BC–220AD), including faience beads, wall paintings, polychrome decoration on pottery, stone and bronze objects, were studied using Raman microscopy and polarized light microscopy (PLM). Chinese Blue (BaCuSi4O10) and Chinese Purple (BaCuSi2O6) were identified, and additionally dark blue particles of a new pigment BaCu2Si2O7 were also detected in purple decoration. Based on PLM observation, Chinese Blue, Chinese Purple and BaCu2Si2O7 frequently coexist in single polychrome samples and cannot be individually identified using other analytical methods because of the minute amount that these chemicals present: sometimes comprising just one or two particles. The use of Raman spectroscopy can identify such small presences. This paper illustrates the man-made barium copper silicate pigments along the Qin historical development and shows the advantage of PLM combined with Raman spectroscopy to analyses pigments giving us an overall picture of the dates and the places where barium copper silicate pigments were used in ancient China. Their origin, decline and manufacturing techniques are also discussed.

Effect of Size of Graphite Flakes on the Physical Properties of the Graphite Materials

Mesophase pitch and natural graphite flake were applied as raw materials to prepare the graphite materials by a hot-pressing technique at a relatively low temperature. In this work, the effect of mean size of natural graphite flake on physical properties and microstructure of the graphite materials were investigated. X-ray analyses, field emission scanning electron microscopy and polarized light microscopy observations indicate that the graphite blocks have highly preferred structural orientation perpendicular to the hot-pressing direction. Results shows that the graphite materials have a low electrical resistivity of 2.45μΩ·m and a high thermal conductivity of 498 W/m·K ,as well as a high bending strength of 26.71 MPa when the mean size of graphite flake in raw materials was 425μm.

Anhydrous proton‐conducting electrolyte based on a nematic poly(methyl acrylate) containing sulfonated side chains

ABSTRACTA nematic poly(methyl acrylate) containing terminal sulfonic acids in side chains was prepared by etherification of a brominated mesomorphic precursor with 2‐hydroxyethanesulfonic acid sodium salt. Differential scanning calorimetry measurements and polarized light microscopy observation revealed that the sulfonated polymer exhibited the nematic mesophase at medium temperatures (189–227°C). Electrochemical impedance spectroscopy measurements showed that temperature dependence of anhydrous proton conductivity for the nematic polymer followed the Arrhenius law and that the estimated activation energy was 95 kJ mol−1 in the nematic phase. The proton conductivities of the nematic polymer were two orders of magnitude higher than those of anhydrous Nafion®117 membrane at the same temperature. The enhanced anhydrous proton conductivities of the polymeric electrolyte were ascribed to the orientational order and fluidity of the nematic liquid crystal. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40382.

Coal petrology characteristics of middlings from Qianjiaying fat coal mine

The objective of this paper is to evaluate the coal petrology characteristics of slack middlings (13–0.5mm) of dense media separation and flotation middlings from Qianjiaying fat coal preparation plant. Phase composition, macerals distribution, microlithotype and mineral occurrence of the two middlings were studied by XRD analysis and polarized light microscopy observation. Macerals distribution and wettability of the float-and-sink products separated from the middlings after grinding was investigated to determine the liberation degree. Studies show that there are more vitrinite and mineral, but less inertinite in slack middlings than in flotation middlings. Macerals associated with mineral in slack middlings is 69.85%, by volume, which is 17.86% higher than that in flotation middlings. Minerals in slack middlings are dominated by pyrite and clay, which are disseminated with the diameter less than 2μm. The main mineral in flotation middlings is clay with size range of 2–20μm. Single macerals in the slack middlings are difficult to liberate due to the fine-grained minerals. After grinding, macerals associated with minerals in the slack middlings decrease to 46.73%, by volume, which is higher than in flotation middlings by 25.89%, by volume. For slack middlings with poor liberation degree, density fractions below 1.8g/cm3 is hydrophobic with contact angle above 71.5°. For the well liberated flotation middlings, there is significant wettability difference among the float-and-sink products. This research is the theoretical basis to realize re-separation of middlings.

A temperature-programmed oxidation method for quantitative characterization of the thermal cokes morphology

A series of thermal cokes obtained by coking of vacuum residues and fractions have been studied by polarized light microscopy observation, scanning electron microscope (SEM), and temperature-programmed oxidation (TPO) technique. The anisotropic degrees of coke samples are found to be considerably different for discriminating characterization, which indicates that the coke morphology is closely dependent on the chemical nature of the coking materials. The restricted mesophase development in thermal coke might be ascribed to the increasing amount of heteroatoms contained in the parent coking materials. A proper signal analysis procedure of TPO profiles was obtained to discriminate the carbon species in the coke quantitatively, and then a good one-to-one correlation between determinations by polarized-light micrographs analysis and TPO method was observed, which shows that the TPO technique could be a suitable and more rapid method than polarized-light microscopy to quantitatively assess the morphology of coke, even in some situations in which the traditional method is inadequate.