Mosaic Texture Research Articles

Mechanism of coal pitch pre-hydrogenation catalyzed by metal-free catalytic system and preparation of mesophase pitch

Coal pitch (CP) molecules have high aromaticity, planarity and condensation degree, usually requiring hydrogenation to prepare high-quality mesophase pitch (MP). However, current hydrogenation methods often face challenges such as harsh conditions, residual ash or insufficient hydrogenation. Here, with 5 wt% tetrahydronaphthalene (THN) as the hydrogen donor, hydrogenated CP (HCP) with low ash content and high H/C was prepared at low temperature and pressure via a metal-free catalytic system with boron trifluoride ether (BF3·Et2O) as catalyst and p-toluenesulfonic acid (TsOH) as co-catalyst and 5 wt%. Subsequently, MP was prepared from the HCP, and the mechanisms of catalytic hydrogenation and the formation of mesophase macromolecules were elucidated. The characterization results indicated that CP achieved optimal hydrogenation when the molar ratio of BF3 to TsOH was 1:1. The HCP obtained under this condition can further prepare a wide-area streamlined MP. During the hydrogenation process, TsOH provided proton hydrogen to BF3, forming a complex acid that facilitated carbocation reactions between THN and CP molecules, thereby enhancing hydrogenation efficiency. However, when the molar amount of TsOH exceeded that of BF3, it would catalyze the polymerization of HCP molecules to a certain extent, reducing the hydrogenation effect. Meanwhile, it could introduce more sulfonic acid groups into the molecular structure, causing cross-linking of polycyclic aromatic hydrocarbons and excessive system viscosity during the preparation of the MP, resulting in a mosaic optical texture. This work is of significant importance for promoting the efficient hydrogenation of CP and the preparation of high-quality MP.

A Novel Approach of Surface Texture Mapping for Cone-Beam Computed Tomography in Image-Guided Surgical Navigation.

The demand for cone-beam computed tomography (CBCT) imaging in clinics, particularly in dentistry, is rapidly increasing. Preoperative surgical planning is crucial to achieving desired treatment outcomes for imaging-guided surgical navigation. However, the lack of surface texture hinders effective communication between clinicians and patients, and the accuracy of superimposing a textured surface onto CBCT volume is limited by dissimilarity and registration based on facial features. To address these issues, this study presents a CBCT imaging system integrated with a monocular camera for reconstructing the texture surface by mapping it onto a 3D surface model created from CBCT images. The proposed method utilizes a geometric calibration tool for accurate mapping of the camera-visible surface with the mosaic texture. Additionally, a novel approach using 3D-2D feature mapping and surface parameterization technology is proposed for texture surface reconstruction. Experimental results, obtained from both real and simulation data, validate the effectiveness of the proposed approach with an error reduction to 0.32 mm and automated generation of integrated images. These findings demonstrate the robustness and high accuracy of our approach, improving the performance of texture mapping in CBCT imaging.

Hydrothermal silicification along rift border faults in the Rio do Peixe basin, Brazil

This study investigates hydrothermal silicification along rift border faults in the Cretaceous Rio do Peixe Basin, Brazil, through field geology, petrography, mineralogy, and fluid inclusion microthermometry. We distinguish three main structural-diagenetic domains: (1) a non-silicified fault damage zone, (2) a silicified damage zone composed of deformation bands and centimeter-scale quartz veins in the hanging wall and footwall, respectively, and (3) a silicified fault core with meter-scale wide quartz veins and mosaic breccia textures. We recognize three main events of silicification in the fault zone. The first silicification event occurs after the widespread development of deformation bands in the hanging wall damage zone that may reach 270 m in width. During subsequent deformation events, multiple fracturing episodes were accompanied with precipitation of the second quartz generation in hydraulic mosaic breccias and the third quartz cement in vein stockworks. Shallow burial conditions of faulting (<2 km), combined with fluid inclusion homogenization temperatures of the second quartz generation, indicate that silicification occurred in a hydrothermal system characterized by fluid temperatures in the range of 71–391 °C (mean value of 141 °C). We conclude that hydrothermal silicification was imprinted during the late synrift stage, when the rift border faults were already established. This contribution has implications for understanding how structural processes may control the geometrical, petrographic and petrophysical attributes of hydrothermal products.

Insights on the regional thermal evolution from semianthracite petrology of the Fengfeng coalfield, China

Igneous intrusions induce alterations in coal and minerals. Alteration degree depends upon the in-situ coal rank and maceral composition, the intrusion temperature, heat source proximity, and intrusion size. In the Permo-Carboniferous Fengfeng coalfield, coal rank increases over some 50 km distance south to north from high volatile bituminous coal to anthracite. The coal seams were commonly intruded, and the regional elevation of rank was augmented by Jurassic-Cretaceous igneous intrusions, not just burial coalification. The petrographic examination of a semianthracite from the Dashucun mine in the north of the Fengfeng coalfield shows development of coke microstructure and increased reflectance approaching the dike in the No. 2 Seam. Based on 11 samples at 50-cm horizontal intervals, random vitrinite reflectance value (Rr) declines from 5.41% at the contact to the background value of 2.05% at 5-m distance from the contact. Towards the dike, vitrinite anisotropy increases and the microtexture shows development of circular, coarse mosaic, and ribbon anisotropic coke textures and devolatilization vacuoles. Natural coke textures respond to an estimated temperature > 570 °C at the intrusion/coal contact. However, the occurrence of coke structures within a semianthracite reveals a local and regional thermal evolution. Coke textures suggest that coal rank was high volatile A bituminous coal at the time of intrusion. This has implications for burial history, heating, and subsidence rates. Assuming a paleogeothermal gradient of 40 °C/km, high volatile A bituminous coal (1% Rr) would have been buried to 3 km at the time of the Jurassic intrusion. The intrusion metamorphosed high volatile bituminous coal to natural coke and subsequent larger-scale regional metamorphism then metamorphosed the coal to semianthracite.

Exploring induced smectic phases of hydrogen bond liquid crystals for nonlinear optical applications: Theoretical (DFT) and experimental approach

A new intermolecular hydrogen bond liquid crystal (HBLC) complex has been isolated and characterized. The HBLC complex is synthesized by mixing of non mesogenic (E)-3-(3,4,5-trimethoxyphenyl)prop‑2-enoic acid (3,4,5-Trimethoxycinnamic acid, TMCA) and mesogenic (E)-3-(4-Methoxyphenyl)prop‑2-enoic acid (4-Methoxycinnamic acid, 4MCA). Mesogenic textures and its LC parameters are analyzed using polarizing optical microscope (POM) and differential scanning calorimeter (DSC). The manifestation of cyclic dimer H-bonds between TMCA and 4MCA is confirmed via FTIR spectrum by observing peak at 3593cm−1 (OH) and C = O at 1683cm−1. It is noteworthy to observe that the induced smectic A (Sm A) with batonnets texture (during cooling cycle) at 129.3 °C and smectic G (Sm G) with multi color mosaic texture at 116.5 °C in TMCA+4MCA, while compared to its individuals. To understand the molecular level modifications in the LC phases, with the aid of density functional theory (DFT), the nature (H-bond length, MEP, FMO, QTAIM, etc.,) and strength of intermolecular H-bonds are explored. The NLO parameters of HBLC complex have been discussed. In this present paper, the DFT result is compared with experimental observations and the special significances are studied to identify the potent applications of HBLCs.

Cinnamic acid and biphenyl core calamitic asymmetric molecules: preparation and characterization for mesomorphic properties

ABSTRACT Some cinnamic acid and biphenyl core-derived calamitic molecules were synthesized and characterized for mesomorphic properties. Newly synthesized compounds showed well-defined schlieren textures and mosaic textures for the nematic phase and a relatively well-organized smectic A phase with focal conic textures. The chemical structures were confirmed by FT-IR, 1H-NMR, 13C-NMR and elemental analysis. The thermotropic behavior, optical textures and thermal stability have been investigated by differential scanning calorimetry (DSC), polarized optical microscopy (POM), X-ray diffraction (SAXS) and thermal gravimetric analysis (TGA) respectively.

Assessment of thermal maturity in Lower Cambrian organic-rich shale in south China using integrated optical reflectance and Raman spectroscopy of pyrobitumen

It is challenging to accurately determine the thermal maturity of Lower Cambrian overmature shale, which is widely distributed in South China. In this study, we report an integrated method of measuring optical reflectance and Raman spectroscopy of pyrobitumen to determine the thermal maturity of Lower Cambrian organic-rich shales that contained a highly aromatized organic matter chemical structure. The optical reflectance measurement was conducted on large-particle-size angular pyrobitumen to eliminate the interference of clay mineral matrix, and the Raman spectrum analysis is a statistical response of a highly thermally evolved pyrobitumen chemical structure. Raman analysis compensates for the limitation of optical anisotropy interference in optical reflectance measurements. There is a good agreement between optically measured pyrobitumen reflectance (PBRo) and pyrobitumen reflectance calculated by Raman parameters (RmcPBRo), reflecting only minimal effects of optical anisotropy on the average optical reflectance (PBRo) values of pyrobitumen with fine or irregular mosaic texture, further indicating reliability of this integrated method for analyzing overmature shale. Thermal maturity varies significantly in the Lower Cambrian organic-rich shales, ranging from 2.60 to 2.92% EqVRo in the western Hubei province (WHBP), 2.98–3.49% EqVRo in the southern Shaanxi province (SSXP), 3.20–3.38% EqVRo in the southern Sichuan province (SSCP) and 4.06–4.31% EqVRo in the southeastern Chongqing (SECQ). The degree of aromatization and the structural order of organic matter (OM) are abruptly intensified when thermal maturity reaches about 3.5–3.7% EqVRo, as indicated by the deconvolution of the D and G bands in the Raman spectrum of pyrobitumen. The abrupt change in chemical structure of OM provides evidence for further dividing the early and late stages of overmaturation at a boundary of 3.5–3.7% EqVRo. The Lower Cambrian organic-rich shales distributed in the Cambrian shale gas breakthrough areas are normally at the early stage of overmaturation (2.0% < EqVRo < 3.5–3.7%). Development of paleo-uplifts in the Cambrian shale gas breakthrough areas led to relatively shallow burial depth of Lower Cambrian shale distributed on the peripheral areas of paleo-uplifts and created favorable shale gas preservation condition with only rare and small-scale faults.

Hydrogenation of coal tar pitch for improved mesophase pitch molecular orientation and carbon fiber processing

The high softening point and mosaic optical textures of coal tar pitch (CTP)-derived mesophase pitches are the main factors limiting their application in high performance carbon fibers. Spinnable mesophase pitch was prepared using CTP hydrogenation process, and the effect of hydrogenation process on the preparation of mesophase pitch and the crystal structure of carbon fibers was investigated. Molecular structure characterization results show that the naphthenic structures and the aliphatic groups in hydrogenated CTP were generated by the hydrogen addition reaction of aromatic rings and the subsequent naphthenic cracking reactions, respectively. The naphthenic structures and aliphatic groups introduced during the CTP hydrogenation process of CTP have a significant effect on improving the homogeneity of anisotropic textures, molecular weight distributions and the molecular stacking heights of mesophase pitches. The prepared mesophase pitch has lower viscosity and enhanced flowability, significantly improving its spinning stability and the molecular orientation of their as-spun pitch fibers. Benefits from this, the optimized carbon fibers present distorted graphite lamellar structures and possess a larger crystal size than commercial coal tar-based carbon fibers K13D2U. The work provides some valuable insights for enhancing crystal structures of carbon fibers via molecular structure regulations of their precursors.

Semantic segmentation of textured mosaics

This paper investigates deep learning (DL)-based semantic segmentation of textured mosaics. Existing popular datasets for mosaic texture segmentation, designed prior to the DL era, have several limitations: (1) training images are single-textured and thus differ from the multi-textured test images; (2) training and test textures are typically cut out from the same raw images, which may hinder model generalization; (3) each test image has its own limited set of training images, thus forcing an inefficient training of one model per test image from few data. We propose two texture segmentation datasets, based on the existing Outex and DTD datasets, that are suitable for training semantic segmentation networks and that address the above limitations: SemSegOutex focuses on materials acquired under controlled conditions, and SemSegDTD focuses on visual attributes of textures acquired in the wild. We also generate a synthetic version of SemSegOutex via texture synthesis that can be used in the same way as standard random data augmentation. Finally, we study the performance of the state-of-the-art DeepLabv3+ for textured mosaic segmentation, which is excellent for SemSegOutex and variable for SemSegDTD. Our datasets allow us to analyze results according to the type of material, visual attributes, various image acquisition artifacts, and natural versus synthetic aspects, yielding new insights into the possible usage of recent DL technologies for texture analysis.

Carbonatitic Magma Fractionation and Contamination Generate Rare Earth Element Enrichment and Mineralization in the Maoniuping Giant REE Deposit, SW China

Abstract Carbonatite intrusions host the world’s most important light rare earth element (LREE) deposits, and their formation generally requires extraordinary fertile sources, magmatic evolution, and hydrothermal events. However, carbonatitic magma evolution, particularly the role of fractional crystallization and contamination from silicate rocks in REE enrichment, remains enigmatic. The Maoniuping world-class REE deposit in southwestern China, is an ideal target to decipher magmatic evolution and related REE enrichment as it shows continuous textual evolution from medium- to coarse-grained calcite carbonatite (carbonatite I) at depth, to progressively pegmatoidal calcite carbonatite (carbonatite II) at shallow levels. In both types of calcite carbonatites, four generations of calcite can be classified according to petrographic and geochemical characteristics. Early-crystalizing calcite (Cal-I and Cal-II) are found in carbonatite I and exhibit equigranular and a polygonal mosaic textures, while late calcites (Cal-III and Cal-IV) in carbonatite II are large-size oikocrysts (&amp;gt;0.5 mm in length) with strain-induced undulatory extinction and bent twinning lamellae. All these generations of calcite yield similar, near-chondritic, Y/Ho ratios (26.6–28.1) and are inferred to be of magmatic origin. Remarkably, gradual enrichment of MgO, FeO and MnO from Cal-I to Cal-IV is coupled with a significant increase in REE contents (~800 to 2000 ppm), with LREE-rich and gentle-to-steep chondrite-normalized REE patterns ((La/Yb)N = 3.1–26.8 and (La/Sm)N = 0.9–3.9, respectively). Such significant REE enrichment is ascribed to protracted magma fractional crystallization with initial low degree of fractional crystallization (fraction of melt remining (F) = ~0.95) evolving to late stage (F = 0.5–0.6) by formation of abundant calcite cumulates. Differential LREE and HREE behavior during magma evolution largely depend on separation of phlogopite, amphibole, and clinopyroxene from the carbonatitic melt, which is indicated by progressively elevated (La/Yb)N ratios ranging from 3.1 to 26.8. The four generations of calcite have significantly different C and Sr isotopic compositions with δ13CV-PDB decreasing from −3.28 to −9.97‰ and 87Sr/86Sr increasing from 0.70613 to 0.70670. According to spatial relations and petrographic observations, the relative enrichment of δ13C and depletion in 87Sr/86Sr ratios of Cal-I and Cal-II show primary isotopic characteristics inherited from initial carbonatitic magma. By contrast, the variable Sr and C isotopic compositions of Cal-III and Cal-IV are interpreted as the results of contamination by components derived from silicate wall rocks and loss of CO2 by decarbonation reactions. To model such contamination processes, Raleigh volatilization and Monte Carlo simulation have been invoked and the model results reveal that carbonatitic melt-wall rock interaction requires 40% radiogenic Sr contamination from silicate rocks and 35% CO2 degassing from carbonatitic melt. Moreover, positive correlations between decreasing δ13C values and increasing REE contents, together with bastnäsite-(Ce) precipitation, indicate further REE accumulation during the contamination processes. In summary, alongside REE-rich magma sources, the extent of fractional crystallization and contamination during carbonatitic magma evolution are inferred to be important mechanisms in terms of REE enrichment and mineralization in carbonatite-related REE deposits worldwide.

Evidence for Solution-Mediated Phase Transitions in Kidney Stones: Phase Transition Exacerbates Kidney Stone Disease

In this study, we investigated calcium oxalate (CaOx) kidney stones and showed direct evidence of the solution-mediated phase transition of calcium oxalate dihydrate (COD; the metastable phase) to calcium oxalate monohydrate (COM; the stable phase). We examined the crystal phases, crystal textures, and protein distributions within thin sections of calcium oxalate kidney stones. Observation with a polarized-light microscope showed that the outline of the mosaic texture, in which COM crystals are assembled in a mosaic pattern, roughly coincides with COD’s crystallographically stable face angles. Microfocus X-ray CT measurement captured the intermediate process of the phase transition, starting inside the COD single crystal and gradually transforming to COM crystals. In addition, the distribution of osteopontin and prothrombin fragment-1, common proteins contained in urine and visualized by multicolor fluorescence immunostaining, showed no apparent striations inside the COM single crystals with the mosaic texture, although the striation is apparent inside the COD single crystals. This is probably because the phase transition of mosaic-like COM occurred in a semiclosed system inside the COD single crystal, so the effect of periodic (day–night, seasonal, etc.) urinary protein concentration changes was small. On the other hand, striations were visible in concentrically laminated COM. This indicated that concentrically laminated COM formed in response to the changes in urinary protein concentrations. From the above, we conclude that the COD single crystals and the concentrically laminated COM seen in CaOx stones are primary structures, and the mosaic COM is a secondary structure that is a pseudomorph formed by the solution-mediated phase transition from COD single crystals.

The mitigation of pitch-derived carbon with different structures on the volume expansion of silicon in Si/C composite anode

The microstructures of carbon precursors significantly affect the electrochemical performance of Si/C composite anodes. However, the interaction between Si and carbon materials with different structures is still unclear. Pitch-based materials undergoing different thermal treatments are superior sources for synthesizing carbons with different structures. Herein, different types of mesophase pitch (domain, flow-domain and mosaic structure) obtained from controllable thermal condensation are utilized to prepare Si/C composite materials and the corresponding models are established through finite element simulation to explore the correlation between the lithium storage properties of Si/C composites and the structures of carbon materials. The results indicate that the flow-domain texture pitch P2 has a better ability to buffer the volume expansion of silicon particles for its highly ordered arrangement of carbon crystallites inside could disperse the swelling stress uniformly alongside the particle surface. The sample Si@P2 exhibits the highest capacity of 1328 mA h/g after 200 cycles at a current density of 0.1 A/g as well as the best rate performance and stability. While sample Si@P3 in which the mosaic texture pitch P3 composed of random orientation of crystallites undergoes the fastest capacity decay. These findings suggest that highly ordered carbon materials are more suitable for the synthesis of Si/C composite anodes and provide insights for understanding the interaction between carbon and silicon during the charging/discharging process.

Oolichan Moon by Samantha Beynon (review)

Reviewed by: Oolichan Moon by Samantha Beynon Kate Quealy-Gainer, Editor Beynon, Samantha Oolichan Moon; illus. by Lucy Trimble. Harbour, 2023 [32p] Trade ed. ISBN 9781550179927 $24.95 Reviewed from digital galleys R 6-9 yrs Big Sister and Little Sister love going to their grandparents, especially when Grandmother prepares food in the traditions of their people, the Nisga'a. Their favorite dish is the oolichan, small fish cooked to mouthwatering perfection. When the girls ask if it is oolichan season, however, Grandmother sits them down for a story, explaining why the fish are called saviour fish by their Elders. Oolichan are often the first fish caught after long winters, restoring their people's storage of fresh food; they have medicinal properties; and their oil has contributed to the Nisga'a ability to trade for food and other goods. Finally, she reveals that the arrival of the oolichan is called Hoobiyee, and—much to the sisters' delight—Hoobiyee is now. Framing a lesson on the fish and its contributions to the Nisga'a within the interactions between the sisters and their grandmother gives this tale a particular warmth, and there's humor to be found in the siblings' bickering over interrupting the story and grandmother's patient telling. Spreads alternate between the simple text against white background with striking, full bleed pages, featuring stylized digital illustrations that balance simple natural lines and curves with mosaic like textures and angles. The setup creates a lovely pace, with each page turn either settling into the coziness of grandmother's lesson or highlighting the beauty of the fish and their connections to the sisters' culture. Beynon, of Nisga'a, Ts'msyen, and European heritage, provides more information about oolichan and Nisga'a culture in the backmatter. Copyright © 2023 The Board of Trustees of the University of Illinois

Magmatic to hydrothermal evolution of the Gaogangshan Mo deposit, NE China: Mineralogical insights from quartz

Integrated study on cathodoluminescence (CL) textures and compositions of quartz is proven to be an effective way to reconstruct the ore-forming conditions and processes of porphyry system under subduction tectonic setting. However, little relevant research has been conducted on collision-type porphyry deposits. The Gaogangshan deposit in the northern Lesser Xing'an Range, NE China, consists of typical collision-type porphyry Mo mineralization related to Permo-Triassic granitic intrusions. Ore-forming process is recorded by multiple generations of quartz, including pre-ore stage quartz with unidirectional solidification texture (UST), early ore-stage quartz-molybdenite veins with K-feldspar alteration halos (Q1), late ore-stage quartz-sulfides veins with sericite alteration (Q2), and post-ore stage quartz veins (Q3) associated with calcite and fluorite. Cathodoluminescent textures, trace elements and fluid inclusions in quartz reveal physicochemical conditions, evolution of ore fluids and the Mo mineralization process. The UST quartz and Q1 veins are dominated by CL-bright homogenous and/or granular mosaic textures, containing more Ti concentrations (average = 35–42 ppm) than Q2 and Q3 veins. The molybdenite-bearing Q2 veins are dominated by CL-gray granular and zonal textures, displaying less CL intensity and lower Ti concentrations (average = 16 ppm) than early-stage quartz. The Q3 veins have the lowest CL-intensity and the lowest Ti concentrations (average = 2.5 ppm) among all quartz types. Three types of inclusions are identified in above quartz samples, including liquid–vapor aqueous inclusions, CO2-bearing liquid–vapor aqueous inclusions and halite-bearing multiphase aqueous inclusions. The ore-forming fluids in ore-stage Q1 and Q2 veins are dominated by large salinity variation (2.3–38.9 wt% NaCl equiv.), CO2-bearing (4.2–8.9 mol%) two-phase aqueous inclusions with vapor volumetric proportions of 30–65%. Intersections of fluid inclusion isochores with Ti-in-quartz isopleths yield quartz formation conditions of ∼2.2 kbar at ∼640℃ for UST quartz, ∼1.25 kbar at ∼510℃ for Q1, ∼1.0 kbar at ∼440℃ for Q2, and ∼0.37 kbar at ∼220℃ for Q3. The Gaogangshan porphyry Mo deposit formed at depths of 3.8 to 4.7 km.

Preparation of mesophase pitch with domain textures by molecular regulation of ethylene tar pitch for boosting the performance of its carbon materials

The fast formation of mosaic optical textures is one of main factors limited its application in high performance carbon materials due to active components containing olefins in ethylene tar pitch (ETP). In this paper, a thermal pretreatment process is proposed for effective molecular reformation of ETP, especially for separation of these active components containing olefins. Mesophase pitch with developed rheological properties and domain anisotropic textures was then prepared via polymerization of the post-treated ETP. Molecular structures analysis results show that these active components containing olefins in ETP prefer to form macromolecules consisted of multiple aromatic cores via rapid radical reactions, and develop a mixed anisotropic texture consequently. Nevertheless, these normal aromatic components tend to produce a semi-rigid molecular structure with less aromatic cores by aliphatic chains transfer reactions and stable radical polymerization reactions. This architecture facilitates its molecular stacking and orientation thus the prepared mesophase pitch (ETP-MP) shows better anisotropic domain texture. The prepared mesophase pitch had suitable performance for the application in needle cokes and carbon foams. This work will help to expand the manufacturing of ETP-derived carbon materials through molecular reformation.

Impact of core polarity on smectic B-induced hydrogen bond liquid crystals.

The novel series of hydrogen bond liquid crystals were synthesized from the 2-methylglutaric acid (MGA) and 4-alkyloxybenzoic acid (nOBA) compounds. The induced smectic B phase with different texture (spine texture, needle texture, mosaic texture, natural mosaic texture and marble texture) were identified by polarizing optical microscope. Due to breaking of in-plane rotational symmetry within molecular layers, smectic B phase is tempted by suppressing other usual mesophases. The mesomorphic transition temperature, enthalpy and entropy values were calculated by differential scanning calorimeter which strongly proves the existence of mesomorphism. H-bond interaction and functional groups were confirmed by the observed peak between 2910 and 2954cm-1 in the FTIR spectra. Thermal stability and extended mesophase width (for MGA + 12OBA = 31.1) of Sm B mesophase were reported and it clearly reveals the existence of mono-phase variance in the MGA + nOBA HBLC complex. Due to the steric effect, and the increased molecular core polarity, the highly stabilized Sm B phase with different textures were observed while varying alkyloxy carbon number n = 7 to 12. Further, the origination of Sm B phase and its detailed characteristics were reported.

Natural growth of gold dendrites within silica gels

Abstract High-grade ores in low-sulfidation epithermal precious metal deposits include banded quartz veins that contain gold dendrites. The processes by which dendrite growth takes place have been subject to debate for decades, especially given that these deposits are known to form from dilute thermal liquids that contain only trace amounts of gold. It is shown here that growth of gold dendrites in epithermal veins at the McLaughlin deposit in California (western USA) originally took place within bands of gel-like noncrystalline silica. The gel provided a framework for the delicate dendrites to form. The high permeability of the gel allowed the diffusion and advection of gold from the thermal liquids flowing across the top of the silica layers to the sites of crystal growth within the gel. Over time, the gel hardened to form opal-AG. This silica phase is thermodynamically unstable and recrystallized to quartz that has a distinct mosaic texture.

Study on preparation of composite carbon rod for high-power electrode from coke with different structural characteristics

Different from lithium-ion batteries, composite carbon rod for high-power electrode was widely used in high-end manufacturing industry due to its good conductivity and low CTE. In this study, semi cokes with different structural characteristics was used as aggregate and coal tar pitch was adopted as binder and impregnant to prepare composite carbon rod for high-power electrode, and the bonding and impregnation behavior was also investigated. It was found that calcination promoted ordered stacking of planar aromatic lamellae of acicular domain texture and aggravated the structural defects of mosaic texture. Coal tar pitch with low aromaticity and high toluene insoluble (TI) as bonded and impregnated pitch possessed higher adhesion but low weight gain ratio after calcination. While higher TI content of coal tar pitch enhanced the weight gain ratio, but the adhesion of composite carbon rod declined. In addition, the carbonaceous sheets derived from coal tar pitch gradually extended and covered the surface of orderly graphited sheets generated from acicular domain texture and contributed to the lowest CTE of 1.43 * 10−6·℃−1 as well as the lowest specific resistance of 6.03μΩ·m. While the structural defects and voids generated from disordered mosaic texture could not be completely filled, thereby resulting in highest CTE of 2.20 * 10−6·℃−1 and highest specific resistance of 9.55μΩ·m.

Co-carbonization of ethylene tar and fluid catalytic cracking decant oil: Development of high-quality needle coke feedstock

In this study, ethylene tar (ET) and refined ethylene tar (ETR) were co-carbonized with fluid catalytic cracking decant oil (DO) to prepare needle coke. The compositions and functional group changes of the blended feedstocks were revealed by Fourier transform infrared spectroscopy and 1H nuclear magnetic resonance. Besides, the carbonization behavior of feedstocks was determined in terms of coke optical observation, carbonized gas composition, and escape rates. The morphology and performance of needle coke were evaluated by scanning electron microscopy and coefficient of thermal expansion. The results showed that the blending of DO to the feedstocks increases the H/C ratio and the content of alkyl and naphthenic structures, which improves the growth and development of the mesophase. However, the coke derived from co-carbonization of ET and DO exhibits a clear separation interface between different optical textures. Further investigation revealed that a large amount of asphaltenes in ET polymerized rapidly into mosaic texture, which hardens prematurely and cannot coalesce with the domain texture subsequently generated by DO. The compatibility of blending ETR and DO for co-carbonization improves significantly after ET is refined to remove asphaltenes. In addition, sufficient gas flow derived from DO promotes the optical microstructure of the resultant cokes by a transition from domain texture into acicular flow type. The synergistic effects between ETR and DO result in the actual CTE and yield of needle coke being lower than the theoretical ones. The CTE of NC-ETRDO50 is lowered to 1.62 × 10-6/°C, being almost the same as that of NC-DO, and the production growth of NC-ETRDO50 is even higher by 7.32% compared with that of NC-DO. Therefore, high-quality needle coke with high production was prepared from low-cost heavy oils.

Detection of phase transitions in liquid crystals through optical, thermal and electrical techniques

A ferroelectric hydrogen bond liquid crystal is chosen for documentation of phase transition temperature by various techniques. In this article, the identification of phase transition from smectic C* to smectic G* through ten various techniques which includes optical, thermal, dielectric and electrical methods are discussed. Optical textures are the first evidence for the phase transition to occur. Smectic C* is manifested by broken focal conic texture while smectic G* is identified by smooth mosaic texture. An intense peak in the DSC thermogram provided the exact phase transition temperature along with enthalpy value of C* to G* phase. The variation of permittivity and dielectric loss with temperature also evinced C* to G* phase transition temperature. In addition to these, thermo-electric profiles of this sample are constructed between voltage and temperature at a fixed magnitude of current. An anomaly in thermo-electric profiles indicated detection of the phase transition temperature. Lastly thermo-resistive profiles are constructed for different values of temperature. An anomaly in the plot between resistance of the mesogen with temperature clearly indicates the first order C* to G* phase transition temperature.