Variation In Mineral Composition Research Articles

Functional Definition of Thyroid Hormone Response Elements Based on a Synthetic STARR-seq Screen.

When bound to thyroid hormone, the nuclear receptor TRα1 activates the transcription of a number of genes in many cell types. It mainly acts by binding DNA as a heterodimer with retinoid X receptors at specific response elements related to the DR4 consensus sequence. However, the number of DR4-like elements in the genome exceed by far the number of occupied sites, indicating that minor variations in nucleotides composition deeply influence the DNA-binding capacity and transactivation activity of TRα1. An improved protocol of synthetic self-transcribing active regulatory region sequencing was used to quantitatively assess the transcriptional activity of thousands of synthetic sites in parallel. This functional screen highlights a strong correlation between the affinity of the heterodimers for DNA and their capacity to mediate the thyroid hormone response.

Variation of plagioclase shape with size in intermediate magmas: a window into incipient plagioclase crystallisation

Volcanic rocks commonly display complex textures acquired both in the magma reservoir and during ascent to the surface. While variations in mineral compositions, sizes and number densities are routinely analysed to reconstruct pre-eruptive magmatic histories, crystal shapes are often assumed to be constant, despite experimental evidence for the sensitivity of crystal habit to magmatic conditions. Here, we develop a new program (ShapeCalc) to calculate 3D shapes from 2D crystal intersection data and apply it to study variations of crystal shape with size for plagioclase microlites (l < 100 µm) in intermediate volcanic rocks. The smallest crystals tend to exhibit prismatic 3D shapes, whereas larger crystals (l > 5–10 µm) show progressively more tabular habits. Crystal growth modelling and experimental constraints indicate that this trend reflects shape evolution during plagioclase growth, with initial growth as prismatic rods and subsequent preferential overgrowth of the intermediate dimension to form tabular shapes. Because overgrowth of very small crystals can strongly affect the external morphology, plagioclase microlite shapes are dependent on the available growth volume per crystal, which decreases during decompression-driven crystallisation as crystal number density increases. Our proposed growth model suggests that the range of crystal shapes developed in a magma is controlled by the temporal evolution of undercooling and total crystal numbers, i.e., distinct cooling/decompression paths. For example, in cases of slow to moderate magma ascent rates and quasi-continuous nucleation, early-formed crystals grow larger and develop tabular shapes, whereas late-stage nucleation produces smaller, prismatic crystals. In contrast, rapid magma ascent may suppress nucleation entirely or, if stalled at shallow depth, may produce a single nucleation burst associated with tabular crystal shapes. Such variation in crystal shapes have diagnostic value and are also an important factor to consider when constructing CSDs and models involving magma rheology.

Bioceramic a futuristic boon in endodontics

Background: The ultimate goal of root canal treatment is prevention or healing of apical periodontitis. The use of biologically active materials to seal root canal systems has been extensively proposed in contemporary endodontics to realise this goal. There are several commercial formulations of bioceramics available based on minor variations in composition which could have potentially important changes in properties in the clinical situation. This narrative review serves to provide brief information on the different formulations of bioactive ceramics that are available to a dentist. Aim: To give an overview of bioceramics used in endodontics, their classification, advantages and disadvantages. This review also gives insights about each biomaterial in detail and its use in endodontics. Review Results: Continuous innovations have led to bioceramics showing a variety of applications in both endodontic and restorative dentistry. While MTA was the benchmark in bioceramics materials, material advances have constantly tried to overcome disadvantages and improve its properties. Conclusion: Bioceramics now have a wide array of applications both in endodontics and restorative dentistry. However, considering the biological advantages of bioceramics materials, their use in multiple paradigms of endodontic therapy appears to be the future.

Variation in mineral composition by hydration and carbonation in calcium hydroxide matrix containing zeolite

Natural zeolite can modify the mechanical properties of concrete as a supplementary cementitious material based on pozzolanic activity. However, the pozzolanic reaction is difficult to explain because of the formation of amorphous reaction products and the complexity of concrete systems. In this study, the mineral, amorphpus phase compositions and pozzolanic reaction mechanism of zeolite were further investigated by performing X-ray diffraction (XRD) and magic angle spinning nuclear magnetic resonance (MAS NMR) analysis. Additionally, the pozzolanic activity of Ca(OH)2 (CH)/zeolite (CHZ, 0–50 wt% proportions of zeolite) specimens was investigated after 1, 3, 7, and 28 d of hydration. The pozzolanic products were identified as C-(A)-S-H gel and monocarboaluminate (AFmc) mineral. Zeolite, having a 5 wt% proportion of CHZ specimens, completely reacted after 3 d of hydration. The optimal zeolite proportion for forming AFmc minerals in CHZ specimens after hydration (HCHZ) was 5 wt%. As the zeolite proportion increased beyond 20 wt%, [Al(OH)4]- tended to react with [SiO(OH)3]- to form aluminosilicate gel instead of AFmc. After carbonation curing (CO2 concentration, 99%; gas pressure, 0.2 MPa; curing time, 2 h), the compressive strength of CHZ specimens (CCHZ) improved by 14–34% compared with that of pure CH specimens. An amorphous phase/calcite ratio of approximately 0.21 might produce an optimum strength resistance property in CCHZ. The heat released from the carbonation was beneficial for the polycondensation reaction of amorphous aluminosilicate to partially form Si[OSi]4 or Al[OSi]4 structures.

The combined effects of ripening degree and fermentation process on biochemical properties of table olives and oils of Ayvalık and Gemlik varieties

Abstract The purpose of this study was to investigate the effect of variety, ripening degree, and also fermentation process on the bioactive compounds of olives, and on the fatty acid compositions of olive oils. The highest oil content was determined in fermented green olives (70.02% in Gemlik variety; 66.87% in Ayvalık variety). The fermentation process caused a notable reduction in both total phenolic content (from 2558.30–2894.40 to 699.10–1087.00 mg/kg), and antioxidant activity values (from 81.46–81.20 to 26.00–63.75%) of green olives in brine. Verbascoside was identified as the main phenolic compound (1150.95–1311.25 mg/kg). It was observed that oleuropein, hydroxytyrosol, tyrosol, and rutin contents of olives decreased after fermentation process. Concerning the fatty acid compositions of olive oils, oleic (70.13–75.47% for Gemlik; 67.36–70.22% for Ayvalık) and linoleic acid (6.18–11.13% for Gemlik; 10.13–12.94% for Ayvalık) contents showed differences regarding variety and maturation degree. However, there are minor variations in fatty acid composition according to fermentation.

Fluid sources in basement-hosted unconformity–uranium ore systems: tourmaline chemistry and boron isotopes from the Patterson Lake corridor deposits, Canada

The Patterson Lake corridor is a new uranium district located on the southwestern margin of the Athabasca Basin. Known resources extend almost 1 km below the unconformity in graphite- and sulfide-bearing shear zones within highly altered metamorphic rocks. Despite different host rocks and greater depths below the unconformity, alteration assemblages (chlorite, illite, kaolinite, tourmaline and hematite), ore grades and textures are typical of unconformity-related deposits. This alteration includes at least three generations of Mg-rich tourmaline (magnesio-foitite). The boron isotopic composition of magnesio-foitite varies with generation: the earliest generation, which is only observed in shallow samples from the Triple R deposit (Tur 1), contain the heaviest isotopic signature ( δ 11 B ≈ 19–26‰), whereas subsequent generations (Tur 2 and Tur 3) yield lighter and more homogeneous isotopic signatures ( δ 11 B ≈ 17.5–19.9‰). These results are consistent with precipitation from low-temperature, NaCl- and CaCl 2 -rich brine(s) derived from an isotopically heavy boron source (e.g. evaporated seawater) that interacted with tourmaline and silicates in the basement rocks and/or fluids derived from depth (with low δ 11 B values). The lower δ 11 B values in paragenetically later magnesio-foitite reflect greater contributions of basement-derived boron over time, whereas minor compositional variations reflect local metal sources (e.g. Cr, V, Ti) and evolving fluid chemistry (decreasing Na and Ca, increasing Mg) over time. The δ 11 B and chemical variation in magnesio-foitite over time reinforce the strong interactions with basement rocks in these systems while supporting incursion of basinal brines well below the unconformity contact. Supplementary material: Complete analytical dataset including reference materials are available at https://doi.org/10.6084/m9.figshare.c.5727555 Thematic collection: This article is part of the Uranium Fluid Pathways collection available at: https://www.lyellcollection.org/cc/uranium-fluid-pathways

Petrophysical analysis and mudstone lithofacies classification of the HRZ shale, North Slope, Alaska

Mudstone is vertically and laterally heterogeneous in terms of variations in mineral composition, organic carbon content, and petrophysical properties. The purpose of this study is to classify mudstone lithofacies within the High Radioactive Zone (HRZ) Shale on the North Slope, Alaska, based upon mineralogy, total organic carbon (TOC), and petrophysical properties to interpret their distributions and depositional/diagenetic environments. We integrate core data from six wells and well logs from 18 wells to analyze the variations in rock properties in the HRZ Shale. Analysis of cores at multiple scales of resolution by techniques, including X-ray diffraction (XRD), trace element geochemistry, pyrolysis, and scanning electron microscopy (SEM) are integrated with conventional and advanced wireline logging suites (including pulsed neutron spectroscopy [PNS]) to map vertical and lateral variation in mudstone lithofacies across the study area. Results show that the HRZ Shale exhibits a high degree of vertical and lateral heterogeneities in mineralogy, TOC, and petrophysical properties. This shale formation is composed of 12 lithofacies: pyritic organic mixed shale, organic mixed shale, pyritic mixed shale, mixed shale, pyritic organic mudstone, organic mudstone, pyritic grey mudstone, grey mudstone, pyritic organic siliceous shale, organic siliceous shale, pyritic siliceous shale, and siliceous shale. Quartz abundance is generally higher in the west, and clay proportions increase from the southwest to the northeast of the study area. The TOC content is variable across the HRZ Shale, ranging from 1.5 to 15 wt%. The lithofacies are influenced by depositional conditions, diagenesis, redox conditions, organic matter productivity, and preservation.

Effects of variety and vintage on the minerals of grape juice from a single vineyard

The mineral composition of wine depends on the soil where the grapes are grown, and therefore has been used to distinguish the geographical origin of different wines. However, several factors, including grape variety and vintage, also alter the mineral content of wine. Here, we measured the concentration of 18 elements in 9–10 grape varieties grown in a single vineyard under the same conditions (soil, weather, pruning, and fertilizer) for three years to explore the variation in mineral composition within a vineyard. In principal component analysis, grape varieties were differentiated by the first principal component (PC1), which was mainly contributed by four elements (Ca, Sr, Ga, and Ba; loading score >0.7), while vintages were differentiated by PC2 and PC3, which were mainly contributed by three (Mg, P, and S) and one (Mn) elements, respectively (loading scores >0.7). Both grape variety and vintage affected grape mineral concentration; however, the extent of variation among grapes from our single vineyard was relatively small in comparison to variations previously reported among grapes from different vineyards.

The Control of Diagenesis and Mineral Assemblages on Brittleness of Mudstones

The variation in mineral composition will affect the rock brittleness, thus the change of mineral assemblages during diagenesis has a potential control on the brittleness of mudstones. In this study, thin section, X-ray diffraction (XRD), and Scanning Electron Microscope (SEM) analyses were used to investigate compositional and microscopic features of mudstones. With the enhancement of diagenesis, three mineral assemblages were divided due to the diagenetic evolution of minerals. Quartz, feldspar, dolomite, chlorite, and illite were regarded as brittle minerals and (quartz + feldspar + dolomite + illite + chlorite)/(detrital mineral + carbonate + clay mineral) was defined as the brittleness evaluation index The mudstone brittleness changed slightly during early diagenesis but increased gradually with enhancement of diagenesis in the late diagenesis stage. Quartz and feldspar were scattered above the clay matrix and the contact of grains was limited, therefore, the contribution of detrital minerals to the brittleness was affected by the properties of clay minerals. The diagenetic transformation of clay minerals resulted in the reduction of ductile components (smectite/I-Sm and kaolinite) and increase of brittle components (illite and chlorite), leading to the enhancement of integral rigidity of the mudstones. Meanwhile, the improved crystallization of carbonate in late diagenesis stage enlarged the carbonate grains which resulted in rigid contact between grains. These results highlighted the influence of diagenesis on mudstone brittleness. Therefore, for evaluation of mudstone brittleness, attention should be paid to the diagenesis process besides mineral composition.

The application of machine learning under supervision in identification of shale lamina combination types — A case study of Chang 73 sub-member organic-rich shales in the Triassic Yanchang Formation, Ordos Basin, NW China

Organic rich laminated shale is one type of favorable reservoirs for exploration and development of continental shale oil in China. However, with limited geological data, it is difficult to predict the spatial distribution of laminated shale with great vertical heterogeneity. To solve this problem, taking Chang 73 sub-member in Yanchang Formation of Ordos Basin as an example, an idea of predicting lamina combinations by combining 'conventional log data — mineral composition prediction — lamina combination type identification' has been worked out based on machine learning under supervision on the premise of adequate knowledge of characteristics of lamina mineral components. First, the main mineral components of the work area were figured out by analyzing core data, and the log data sensitive to changes of the mineral components was extracted; then machine learning was used to construct the mapping relationship between the two; based on the variations in mineral composition, the lamina combination types in typical wells of the research area were identified to verify the method. The results show the approach of 'conventional log data — mineral composition prediction — lamina combination type identification' works well in identifying the types of shale lamina combinations. The approach was applied to Chang 73 sub-member in Yanchang Formation of Ordos Basin to find out planar distribution characteristics of the laminae.

Osmium Isotopic Evidence for Eccentricity‐Paced Increases in Continental Weathering During the Latest Hauterivian, Early Cretaceous

AbstractThe 405‐kyr eccentricity cycle is a consistent orbital parameter throughout the Phanerozoic that is associated with long‐term variations in global continental weathering. However, a lack of reliable geological evidence has hampered the understanding of the relation between the 405‐kyr eccentricity cycle and continental weathering during the Cretaceous. Os isotopic ratios (187Os/188Os) of the sedimentary record reflect the balance between radiogenic Os derived from continental weathering and Os derived from unradiogenic sources (e.g., hydrothermal activity, weathering of mafic rocks, and extraterrestrial sources). This ratio is therefore considered as a good proxy for the evaluation of short‐term changes in continental weathering patterns. To trace orbital‐paced continental weathering, this study reconstructs the marine Os isotopic records in upper Hauterivian to lower Barremian (Lower Cretaceous) carbonate rocks in central Italy, where previous studies have reported that variations in clay mineral composition are paced by the 405‐kyr cycle. Our new Os isotopic record documents periodic oscillations of187Os/188Os between 0.7 and 0.9 that correspond to the 405‐kyr Earth's eccentricity cycle. Because the sedimentary interval with radiogenic187Os/188Os values (∼0.9) corresponds to a time interval characterized by a humid climate in areas surrounding the Tethys, variations in the187Os/188O values likely reflect cyclic changes in continental weathering caused by eccentricity‐paced intensification of monsoonal activity at low latitudes. This variation could have been further amplified by increased input of radiogenic Os from Paleozoic shale and Precambrian crust at higher latitudes that resulted from a latitudinal shift of the intertropical convergence zone.

Influence of supercritical CO2 exposure on water wettability of shale: Implications for CO2 sequestration and shale gas recovery

The wettability of reservoir rocks is considered to be closely related to fluid distribution and CO2 geo-storage (CGS) security after injecting CO2 into reservoir. To investigate the influence of supercritical CO2 (ScCO2) injection on water wettability of shale, a sessile drop method was used to measure water contact angles of shale samples collected from Sichuan Basin (marine) and Ordos Basin (continental) at different ScCO2 exposure time and pressure. In addition, X-ray diffraction (XRD) and low-pressure N2 adsorption (LP-NA) were performed to evaluate the variations of mineral compositions and pore structure of shale. Results indicate that shale-water contact angles generally increased (from 22.74% to 43.94%) after ScCO2 exposure, which is primarily caused by the decrease of clay minerals and carbonates in shale. The water wettability of shale weakened after ScCO2 exposure, indicating that the interaction force between shale and water molecules changed, which may have reduced the resistance of water to flow in pores and fractures of shale, inferring that the alterations of shale water wettability after ScCO2 injection is beneficial to gas seepage in pore channels, but may exert a negative influence on CGS stability. This study provides a theoretical reference for CO2 sequestration and CO2-enhanced shale gas recovery (CS-ESGR).

Aqueous core microcapsules as potential long-acting release systems for hydrophilic drugs

We have previously optimized the internal phase separation process to give rise to aqueous core microcapsules with polymeric shells composed of poly(lactide-co-glycolide) (PLGA) or poly(lactide) (PLA). In this study, the ability of these microcapsules to act as controlled release platforms of the model hydrophilic drug phenobarbital sodium was tested. Furthermore, the effect of the initial amounts of drug and water added to the system during microcapsule synthesis was investigated. Finally, the effect of varying polymer properties such as end functionalities, molecular weights, and lactide to glycolide ratios, on the characteristics of the produced microcapsules was studied. This was done by utilizing seven different grades of the polyester polymers. It was demonstrated that, within certain limits, drug loading is nearly proportional to the initial amounts of drug and water. Furthermore, drug encapsulation studies demonstrated that ester termination and increases in polymeric molecular weight result in lower drug loading and encapsulation efficiency. Moreover, drug release studies demonstrated that ester termination, increases in molecular weight, and increases in the lactide to glycolide ratio all result in slower drug release; this grants the ability to tailor the drug release duration from a few days to several weeks. In conclusion, such minor variations in polymer characteristics and formulation composition can result in dramatic changes in the properties of the produced microcapsules. These changes can be fine-tuned to obtain desirable long-acting microcapsules capable of encapsulating a variety of hydrophilic drugs which can be used in a wide range of applications.

Paleoproterozoic ca. 2.2 Ga high-Cl metagabbro in the Belomorian province, Eastern Fennoscandian Shield: Origin and tectonic implications

Tectonic and fluid reworking of deep-seated mafic intrusions in the orogenic belts often erase primary magmatic characteristics, and crystallization parameters of mafic melts enriched in volatiles remain an issue. This study presents new U-Pb geochronological data for zircons, mineral composition, whole-rock geochemistry and Sr-Nd isotopic data for Pechnoy ca. 2.2 Ga mafic layered sill in the central Belomorian province, Eastern Fennoscandian Shield. The Pechnoy intrusion comprises low-alumina, silica-undersaturated, Cl enriched mafic rocks depleted in HREE and HFSE with εNd values of -0.1–+1.5 and (87Sr/86Sr)2200 = 0.7024–0.7039. Field and petrological studies indicate that studied rocks preserved relicts of primary magmatic characteristics because it was encapsulated in host gabbronorite intrusion and avoided intensive fluid reworking during 1.8-2.0 Ga Lapland-Kola orogeny. Variations of mineral composition, major, and trace elements within intrusion originated via in situ fractional crystallization with dominated settling of clinopyroxene and plagioclase. Chlorine distribution within intrusion and in the host rocks inferred a magmatic origin Cl enrichment. High-Na scapolite is the main concentrator of the Cl in the rocks. The inclusions of scapolite in the relict magmatic plagioclase and higher Ca content relative to adjacent Na-rich plagioclase likely indicate early crystallization of high-Na scapolite. Trace element and isotopic characteristics of rocks indicate OIB and subduction modified SCLM signatures of their primary melts. A comparison of the available data for Pechnoy sill and coeval mafic sills in the Karelian Craton reveals a common mantle source for ca. 2.2. Ga igneous rocks in the Fennoscandian Shield although intrusions in the Belomorian province represent deeper levels of 2.2 Ga large igneous province plumbing system.

Mechanical performance and residual stress of WC-Co coatings manufactured by Kinetic Metallization™

Electrolytic hard chrome (EHC) plating is a source of environmental pollution due to evolution of hexavalent chromium, which is a known carcinogen. Coating technology known as Kinetic Metallization™ (KM™) is an alternative to EHC for depositing wear resistant WC-Co coatings. Kinetic Metallization™ employs high kinetic energy of impacted feedstock particles and achieves a dense coating with good intersplat bonding. However, the high kinetic energy imparts peening and thermal stresses that are different from other thermal spray processes. This work characterizes the residual stress profile and room temperature wear behaviour of WC-Co coatings deposited under several input parameters. A combination of SEM imaging and etched optical micrographs revealed significant plastic deformation and particle penetration at the interface due to high energy impact of feedstock particles. No signs of substrate grain refinement were detected. The coating was composed primarily of WC and Co with minor compositional variations, as calculated by quantitative Rietveld analysis, with respect to the input parameters. Coating residual stresses were compressive in nature due to domination of thermal contraction stresses over peening stresses. The wear resistance assessed by the pin-on-disk method revealed a wear performance equivalent to conventionally sprayed WC-Co coatings.

Contribution of continuously stable sediment input to the formation of the Pearl River delta since the middle Holocene

Pearl River sediments have been reported to have changed greatly in composition due to the impact of human activities on erosion and landscapes in southern China since 2500 years BP. Here, sediments from four cores (PRD-1, PRD-3, PRD-6 and PRD-7) from the Pearl River Delta (PRD) were collected for high-density clay mineral analyses to determine the vertical variations in clay mineral compositions since the middle Holocene. The results showed that the clay mineral compositions of these four cores remained constant. In the PRD, the clay mineral assemblage dominantly consists of illite and kaolinite (averaging more than 85%), with smaller amounts of chlorite (averaging 10%) and scarce smectite (averaging 1%). The stable clay mineral assemblages in the PRD confirm that the clay mineral compositions of the sediments continuously supplied by the Pearl River have not changed. However, the smectite percentage in core PRD-7 increased by 7% downward from a depth of 12.4 m, which was correlated with the weathering of local volcanic materials and sediment transport in the east of the Pearl River under the influence of the Guangdong coastal current in winter. The stable clay mineral compositions in the core sediments indicate that the Pearl River sediments have accumulated naturally in the PRD instead of under the influence of human activities, which would have altered the compositions of the core sediments.

Clay mineral composition of upland soils and its implication for pedogenesis and soil taxonomy in subtropical China

Clay minerals are intermediate products generated during soil development, and their neoformation and transformation are closely related to pedogenesis. Here we aimed at identifying the difference in the clay mineral composition of upland soils derived from different parent materials and different soil-forming environments and exploring the importance of clay mineral composition in pedogenesis and soil taxonomy. We sampled 60 soil B horizons in Hunan Province of subtropical China by digging soils derived from granite (GR), slate and shale (SS), Quaternary red clay (QRC), limestone (LS), and sandstone (SDS). The clay mineral composition and its correlation with parent materials, elevation, micro-topography, and pedogenic processes were investigated using X-ray diffraction and Pearson’s correlation analysis. The clay mineral was dominated by kaolinite, followed by 2:1-type minerals (illite and vermiculite), and a small fraction of mixed-layer minerals. The composition of soil clay minerals varied with parent materials. Kaolinite was predominant in soils derived from GR and LS; mixed-layer minerals prevailed in QRC, whereas illite and vermiculite were prevalent in SDS. In addition, elevation and micro-climate could also explain the variations in clay mineral composition. Increase in elevation was associated with decreased 1:1 clay mineral content and increased 2:1 clay mineral content, especially in soils developed from LS. The composition and content of clay minerals indicated that Ferrosols, Ultisols, and Acrisols had undergone intense weathering; Primosols, Entisols, and Leptosols were characterised by weak weathering, and Plinthic Ali-Udic Cambosols, Plinthudults, and Plinthosols were characterised by strong redox status. This study suggests that clay mineral composition is related to the parent material, climate, and micro-topography, and that it can serve as an indicator of pedogenesis and soil type in subtropical China.

A critical review of the common thermocouple reference functions

The use of thermocouples in many present-day applications can often occur with little consideration as to the inherited historical burden of the reference functions the thermocouples must meet. For base-metal thermocouples, the reference functions are specified by equations relating temperature to electro-motive-force and not by alloy composition. Most of the common thermocouples contain at least one alloyed thermoelement, the bulk of which are now known to be inherently unstable above 200 °C. As manufacturing technologies change, along with the material feedstock from which thermocouples are made, modern thermocouples can frequently give measurements that deviate significantly from the ASTM and IEC standards. This study first reviews the development of the thermocouple alloys and historical conditions under which the reference functions were derived and contrasts this with modern thermocouple alloys and new testing methods. From this comparison, it is shown that users of modern base-metal thermocouples need to be extremely cautious when anticipating likely behaviour, with even short exposures to modest temperatures revealing a myriad of manufacturer-dependent instabilities. Minor variations in composition are shown to strongly influence reversible crystallographic ordering effects in addition to passivation behaviour at high temperatures, in some instances leading to catastrophic failure. It is also shown that the initial anneal state given by the manufacturer has a significant effect on the stability and hence, drift rate, with inadequate anneal leading to unnecessarily large drift rates at less than 200 °C. Lastly, this review looks at recent attempts to develop more-stable thermocouples, based on state-of-the-art techniques able to identify specific causes of instability in many of the historic thermocouple alloys and demonstrates how these new thermocouples might better serve the end user’s needs.

Predicting effective thermal conductivity in sands using an artificial neural network with multiscale microstructural parameters

Accurate and efficient prediction of thermal conductivity of sands is challenging due to the variations in particle size, shape, connectivity and mineral compositions, and external conditions. Artificial Neural Networks (ANN) models have been used to predict the effective thermal conductivity but they have not considered variables related to particle connectivity. This work uses computed tomography (CT) scanned images of four dry sands and network analysis to redress this significant shortcoming. Here sands are represented as networks of nodes (grains) and edges (interparticle contacts or/and small gaps between neighbouring particles) to extract network features that characterise interparticle connectivity. A network feature – weighted coordination number (WCN) capturing both particle connectivity and contact area – was found to be a good predictor of effective thermal conductivity in dry materials. Roundness, sphericity, solid particle thermal conductivity and porosity are other input parameters rigorously selected for an ANN model that predicts well the effective thermal conductivity of sands.

Effect of supercritical CO2 extraction on CO2/CH4 competitive adsorption in Yanchang shale

Competitive adsorption characteristics of CO2/CH4 on shales before and after supercritical CO2 (ScCO2) extraction are closely related to CO2 injection in shale reservoir for CO2 sequestration and enhanced shale gas recovery (CS-ESGR). Using a self-developed PCTPro-type automatic high-pressure gas adsorption instrument, the adsorption behaviors of CH4, CO2 and their mixtures with different ratios were investigated on raw and ScCO2-treated (10 day/16 MPa/40 °C) shale collected from the Ordos Basin. The influences of ScCO2 extraction, pressure and CO2/CH4 cratios on adsorption capacity and selective adsorption factor of CO2/CH4 (SCO2/CH4) of shale have been analyzed. To interpret the experimental data, total organic carbon (TOC) analysis, X-ray diffraction (XRD) analysis, low-pressure gases adsorption and mercury intrusion were performed to evaluate the variations of mineral compositions and pore structure of shale exposure to ScCO2. It is found that SCO2/CH4 and the adsorption capacity of CO2/CH4 with different ratios decreased after ScCO2 extraction and are mainly attributable to the decrease of TOC, carbonates, clay minerals and specific surface area in ScCO2-treated shale. The feasibility of CS-ESGR cannot be affected by ScCO2 due to the values of SCO2/CH4 are always greater than 2.5 after ScCO2 extraction. Additionally, SCO2/CH4 decreased initially and then tended to be stable with increasing pressure, and it decreased slightly with increasing CH4 concentration in gas mixtures, suggesting that the reservoir pressure should be lowered before the injection of CO2 into shale reservoir, and the efficiency and engineering cost of CS-ESGR should be considered comprehensively. This study provides a reference for future optimization design of CS-ESGR.