Outer Zone Research Articles

Persistence and expansion of hypoxia detected by pimonidazole adduct immunostaining during progression of diabetic nephropathy in diabetic mice.

Hypoxia and oxidative stress are considered to be underlying factors in the deterioration of renal function and pathogenesis in acute kidney injury (AKI) and chronic kidney disease, including diabetic nephropathy (DN). However, the long-term role of hypoxia in DN is unknown. Here, we investigated the distribution, severity, and time course of hypoxia during DN development in our well-established severely diabetic transgenic (Tg) DN mouse model that mimics human DN up to 80 wk of age, using pimonidazole adduct immunohistochemistry. The relationship between pimonidazole adduct distribution and hypoxia-inducible factor (HIF) expression was also examined. We found 1) persistent pimonidazole immunostaining mainly in the outer zone of the outer medulla, extending into the inner zone, 2) significant expansion of area and intensity up to 40 wk of age, and 3) characteristic subcellular localization mainly at apical sites in vesicular form by laser scanning microscopy of thin slices. The distribution of pimonidazole adducts was different from that of HIF reported previously, indicating that hypoxia does not directly contribute to persistent abnormal HIF expression. These results suggest that pimonidazole adducts produced under low [Formula: see text] conditions are sustained by a mechanism distinct from direct ischemia. We propose that in the long course of DN development, persistent hyperfiltration and hyperexcretion of glucose, albumin, and water increase metabolism and energy expenditure in the tubules, and such chronic stimulation leads to relative ischemia and local hypoxia, which may contribute in part to the loss of nephrons.NEW & NOTEWORTHY This study provides new insights into hypoxia during the long course of diabetic nephropathy development. Hypoxia was persistently localized only in limited areas and its distribution differed significantly from that of hypoxia-inducible factors. These findings suggests that in the long course of diabetic nephropathy development, increased energy requirements and limited blood supply may lead to relative ischemia and induction of local and persistent hypoxia, which may contribute in part to the loss of nephrons.

Compositional Variation and Crystal-Chemical Characterization of a Watermelon Variety of Tourmaline from Anjanabonoina, Central Madagascar

A polychrome tourmaline crystal from Anjanabonoina pegmatite (Madagascar) was characterized using a multi-analytical approach. The sample showed a complex concentric zoning and a wide range of colors typical of the variety known as “watermelon”. The sample was cut perpendicularly to the c axis. The basal slice exhibits a rim characterized by narrow, differently colored layers parallel to the prism faces and a relatively homogeneous triangular core. Four main pronounced color zones were identified from the rim to core: a dark green rim (M1RVS); a pale green rim (M1RVC); a pale pink rim (M1CR); and a brownish yellow core (M1CG). Compositional variations in the basal slice were studied by scanning electron microscopy and electron microprobe analyses (WDS mode). The Li content was determined via micro-laser-induced breakdown spectroscopy. To deeply characterize the sample, single crystal structure refinement was also performed on fragments extracted from the four zones. The results show that the polychrome tourmaline sample consists of two different species: the three outer zones are Mn-rich fluor-liddicoatite, whereas the inner zone is Mn-rich fluor-elbaite. The structural and compositional characterization of the color zoning shows that each step of the tourmaline growth is related to a change in the geological environment.

Assessing the spatial distribution of meiofaunal communities in Krossfjord, Svalbard Archipelago: Foraminifera diversity as a key component

The study furnishes an insight into the ecology of meiofauna through an elaborate examination of the living Foraminifera in the Krossfjorden system of the Svalbard Archipelago. Samples collected during the Summer Phase Indian Arctic Expeditions of 2017 and 2018 were analyzed to reveal novel insights into the distribution, abundance and species composition of living Foraminifera in this less studied fjord system. The investigation uncovered a rich and diverse meiofaunal community consisting of ten taxonomic groups, among which living Foraminifera emerged as a prominent component. The spatial patterns of Foraminifera distribution were examined, revealing their preferences for specific habitats and environmental conditions within the Krossfjorden system. The Shannon diversity index (H’) indicates good overall diversity of foraminifera in the Krossfjord region, with H’ ranging from 4.49 to 4.891 in 2017 and from 3.885 to 4.984 in 2018. The research discovered noteworthy inequalities in the distribution of Foraminifera species amid inner and outer stations, as inferred by PERMANOVA analysis (p<0.05). The foraminiferan species Nonionellina labradorica was the dominant species in outer, middle and inner zones in the fjord, while species Lobatula lobatula, Quinqueloculina seminulum, Hormosinella sp., and Procerolagena sp. played significant roles in driving the dissimilarity between outer, middle, and inner zones. Environmental factors accounted for a substantial 83.1% of the variations observed in foraminiferan species distribution across four CCA axes. The fluctuations in potential temperature, sand fraction, chlorophyll-a, C:N ratio, organic matter, and salinity have had a noteworthy effect on the distribution of species. These findings underscore the susceptibility of Foraminifera and the broader meiofaunal community to the impacts of environmental variations in this rapidly changing Arctic ecosystem. The outcomes of this research provide a crucial baseline for understanding the ecological dynamics of meiofaunal communities in the Krossfjorden system, contributing to predicting future changes in benthic habitats, including the potential repercussions for meiobenthic productivity.

Study on the Reservoir Heterogeneity of Different Volcanic Facies Based on Electrical Imaging Log in the Liaohe Eastern Sag

The volcanic rocks of the Es3 Formation (the third member of the Eocene Shahejie) in the Liaohe Eastern Sag can be divided into four facies and twelve subfacies. The porosity spectrum, porosity bin, variation coefficient (VC), and porosity width derived from electrical imaging log data were applied to study and characterize the heterogeneity of four facies and nine subfacies, both qualitatively and quantitatively. However, the VC and porosity width cannot be used to quantitatively classify heterogeneity when the VC is small and the porosity width is large. In the present study, the authors propose a new parameter, Pvcd = variation coefficient × porosity width. Based on this parameter, using a combination of porosity spectra, porosity bin features, VC, and porosity width, lithofacies heterogeneity is divided into three categories. The first is weak heterogeneity, which has a Pvcd &lt; 1.1, a VC &lt; 0.15, and a porosity width &lt; 6. The second is moderate heterogeneity, which has a Pvcd 1.1–1.6, a VC 0.15–0.25, and a porosity width 6–9. The third is strong heterogeneity, which has a Pvcd &gt; 1.6, a porosity VC &gt; 0.25, and a porosity width &gt; 9. In these three cases, the porosity spectra mainly display unimodal features, the porosity bins are concentrated, the bimodal features with tails and porosity bins are less concentrated, or the multimodal features with tails and porosity bins are scattered, respectively. Favorable reservoirs of volcanic rocks are controlled by lithofacies. In the study area, the favorable reservoirs appear to be the diatreme subfacies with low or medium heterogeneity, the pyroclastic flow subfacies with low heterogeneity, the compound lava flow subfacies with low or medium heterogeneity, and the outer zone subfacies with strong heterogeneity.

A Numerical Study of Flow Structures and Flame Shape Transition in Swirl-Stabilized Turbulent Premixed Flames Subject to Local Extinction

ABSTRACT Large Eddy Simulations (LES) of turbulent lean-premixed flames of V- and M-shape are presented. A simple algebraic closure with the ability to capture finite-rate chemistry effects is used for subgrid reaction rate modeling. The V-shaped flame is stabilized in the inner shear layer between a swirling annular jet and a central recirculating bubble in a sudden expansion duct. The M-shaped flame is stabilized in the inner and outer shear layer, adjoining the corner recirculation zone induced by the vertical step. The focus of the study is on the flow fields and shapes of the flames, which distinguish themselves through different heat load and sensitivity to local extinction. Good agreement with measurements is observed for the cold and the reacting flow cases. The numerical results suggest that the entrainment of hot gases into the outer recirculation zone occurs close to the impingement point of the swirling annular jet on the wall and this process is strongly dependent on intense vortical structures in the outer shear layer. The results further suggest that local extinction influences the position of the flame in the inner shear layer and, thereby, also the intensity of the local entrainment process.

Mineralogy of Agates with Amethyst from the Tevinskoye Deposit (Northern Kamchatka, Russia)

The Tevinskoye agate deposit is located in the North of the Kamchatka peninsula (Russia) and represented by agate-bearing Eocene basaltic and andesitic rocks of the Kinkilsk complex. Agate mineralization occurs in lavas and tuffs as amygdales, geodes, lenses and veins, which are the main sources of the resupply of coastal agate placers. The present study aimed to perform a comprehensive mineralogical, geochemical, and O-isotope investigation of amethyst-bearing agates, and to evaluate data concerning the origin of mineralization and the conditions for amethyst formation. Agates exhibit spectacular textures, with variation in the sequence of silica filling of amygdales and geodes. The mineral composition of the agates is mainly represented by micro- and macro-crystalline quartz, amethyst, length-fast and zebraic chalcedony, moganite, goethite, and clinoptilolite. Carbonate forms individual bands in the outer zones of some agates. The presence of small amounts of native copper, covellite, chalcopyrite and pyrite is a feature of these agates. Copper and iron mineralization are probably typomorphic features related to the host rock composition. The measured values of crystallite size (525–560 Å) and the high moganite content (up to 50%) of agate with amethyst are evidenced by the young age (~45 Ma) of agate-hosting rocks. Agate formation temperatures (21–229 °C) were calculated from the O-isotope composition of chalcedony (+19.6 to +25.5‰), quartz (+18.1 to +22.3‰), and amethyst (+18.2 to +21.5‰). The cold-water monophase fluid inclusions revealed in amethyst crystals suggest that the mineralizing fluids have low temperatures (&lt;100 °C) and low salinity. Magnetite grains in host rock, together with goethite inclusions identified within the amethyst crystals, point to a change in redox conditions and the presence of iron in the agate-forming fluids, which entered the quartz lattice during crystallization and influenced the formation of the violet color.

Assessing the Relationship between Ecological Water Demand of Haloxlon ammodendron and Its Wind Erosion Prevention Effect

Desert vegetation in the outer transition zone of an arid oasis serves as a protective barrier against wind and sand, safeguarding the oasis ecosystem. However, intensive agricultural water usage within the oasis has led to water depletion, posing a threat to the survival and growth of desert vegetation, as well as the associated increase in wind and sand phenomena. To ensure the sustainable distribution of water resources and maintain the stability of the oasis peripheral ecosystem, this study aimed to investigate the relationship between the ecological water demand of desert vegetation and its effectiveness in preventing wind erosion. Through a combination of field sample tests, field pit tests, and data analysis, this research focused on Haloxlon ammodendron, the most prevalent species on the oasis periphery, to explore the intricate relationship between its ecological water demand and resistance to wind erosion. The results showed that medium-vegetation-coverage soils exhibited a higher soil moisture content (7.02%) compared to high-vegetation-coverage soils (1.57%) and low-vegetation-coverage soils (3.41%). As the soil water content decreased, the growth rate of H. ammodendron’s plant height, new branches, and crown width decelerated. The ecological water requirement of H. ammodendron during its growth period was 70.95 mm under medium-vegetation-coverage conditions, exhibiting a significant increase of 14.6% and 12.3% compared to high- and low-vegetation-coverage conditions, respectively. Meanwhile, H. ammodendron exhibits remarkable wind erosion prevention effects in moderate coverage conditions, resulting in a significant reduction in surface sand collection and sand transport by 53.15% and 51.29%, respectively, compared to low vegetation coverage; however, no significant difference was observed when compared to high vegetation coverage. The SEM model results revealed that soil water content had an indirect effect on sand transport (R2 = 0.90) and sand collection (R2 = 0.96) through three pathways of action, namely: volatile water content–crown growth rate–wind speed–sediment discharge; volatile water content–plant height growth rate–vegetation coverage–wind speed–sediment discharge; and volatile water content–plant height growth rate–vegetation coverage–sediment accumulation. This study provides valuable insights for the scientific formulation and implementation of strategies aimed at protecting desert vegetation.

Regional specific tunable meniscus decellularized extracellular matrix (MdECM) reinforced bioink promotes anistropic meniscus regeneration

The healing of meniscus injuries poses a significant challenge, as prolonged failure to heal can lead to osteoarthritis, which presents a therapeutic dilemma in the field of sports medicine. Decellularized extracellular matrix (MdECM) derived from natural meniscus, and the incorporated growth factors have been used for potential fibrochondrocyte induction and meniscus regeneration. However, homogeneous MdECM is difficult to achieve region-specific biomimetic microenvironment for tissue regeneration. In this study, we successfully prepared a region-specific MdECM, which were then mixed with an ultraviolet responsible Gelatin Methacryloyl (GelMA)/hyaluronic acid Methacryloy (HAMA) hydrogel incorporated with bioactive factors, faciliatated a functional region-specific bioink. The 3D printed scaffold by anistropic MdECM and zonally designed microstructure could promote chondrogenic differentiation of inner region cells and fibrochondrogenic differentiation of outer zone cell, ultimately enhanced anisotropic meniscus regeneration and cartilage protection.

Modeling a solar pressurized volumetric receiver integrated in a parabolic dish: Off-design heat transfers, temperatures, and efficiencies

Concentrated solar power plants are commonly recognized as one of the most attractive options within carbon-free power generation technologies because of their high efficiency and feasible hybridization and/or storage implementation. In this work, a complete heat transfer analysis for an air volumetric receiver coupled to a parabolic dish focused on distributed generation (in the range of kWe) is carried out. It includes most relevant heat losses. Dish collector optical efficiency is computed by means of a ray-tracing software while the thermal performance of the solar receiver is modeled under steady-state conditions using a comprehensive set of equations with a clear physical origin and meaning. Detailed information on the temperatures and heat transfers along the different inner and outer receiver zones are computed with a built from scratch in-house code programmed in Mathematica®. The model considers the main losses from convection, conduction and radiation and through the surrounding insulator. The resulting thermal efficiency mainly depends on the incoming solar irradiance at the glass window, the receiver geometry and the type of materials considered, as well as on the ambient temperature. Explicit numerical results are given at two locations under different meteorological conditions. Optical efficiencies reach values of about 84%. For irradiance values around 800–900 W/m2, at the receiver outlet, air can reach temperatures of about 1200K and receiver thermal efficiency is over 80%. It is expected that this model (precise but not too expensive from the computational viewpoint) could help to identify the main efficiency bottlenecks, paving the way for optimization when designing this type of concentrated solar plants through further coupling with a power block, as Brayton or other cycles.

Geochemistry of Neogene Nansatsu volcanic rocks in South Kyushu, Japan

ABSTRACT We report the whole-rock major and trace element and Sr – Nd – Pb isotopic compositions of volcanic rocks from the Nansatsu area in South Kyushu. We analysed samples from the Oldest stage (middle Miocene), Older stage (late Miocene), and Middle stage (early Pliocene) Nansatsu volcanic rocks, which are andesite to dacite in composition, with an island-arc trace element signature. The compositional variabilities within the Older and the Middle stage rocks are relatively small compared to those in the Oldest stage and Quaternary volcanic rocks. Isotopic characteristics suggested that the Oldest stage volcanic rocks had magma sources similar to regional ilmenite-series granitoids of later ages (Outer Zone granitoids), which incorporated a substantial amount of graphite-bearing accretionary sediments (Shimanto Supergroup). The sources for the Older and Middle stage magmas were similar to those of primary Quaternary basalts in South Kyushu, indicating that Pliocene and Quaternary volcanic rocks in South Kyushu share a common mantle source, despite the change in the nature of volcanic activity from andesite-dominated to more variable volcanism of basalt to rhyolite.

Characteristics of High‐Energy Protons in the Equatorial Plane of Inner Radiation Belt Observed by Van Allen Probes

AbstractLong‐term and short‐term variations of high‐energy protons in the inner radiation belt are of major importance in geospace research. The entire inner radiation belt at 1.1 &lt; L &lt; 3.0 have been investigated based on Van Allen Probes Relativistic Electron‐Proton Telescope data during the descending phase of the solar cycle (2013–2018). It is found that two belts with peaks near L = 1.5 and L = 2.0 for E &lt; 50 MeV protons and one belt at L = 1.5 for E &gt; 50 MeV protons, once they are formed, last for more than 6 years. In the outer zone of the inner belt (1.8 &lt; L &lt; 2.4), the variations of high‐energy proton fluxes with E &lt; 50 MeV are well correlated with SYM‐H index, while only weak correlation is found for them in the inner region at 1.3 &lt; L &lt; 1.6. Geomagnetic disturbances do not show clear correlation with variations for E &gt; 50 MeV protons in the whole inner radiation belt. By analyzing the structure evolution of the inner radiation belt during half of the solar cycle, we found that the entire inner radiation belt shrinks at solar minimum and stretches at solar maximum. Our results reveal the relationship between high‐energy protons and SYM‐H index and solar cycle modulation on the whole configuration of inner radiation belt, which may assist in understanding and modeling of the inner radiation belt protons.

Genesis of the Kuh-Panj porphyry copper deposit, Kerman, Iran: Constraints from mineralization, geochemistry, fluid inclusion, and zircon U[sbnd]Pb isotope systematics

The Miocene Kuh-Panj porphyry copper deposit, with reserve estimated at about 100 Mt. at 0.21 % Cu, is located 120 km SW of Kerman in the southern part of the Urumieh-Dokhtar magmatic arc. The Eocene host rocks consist of tuff, lithic tuff, breccia tuff, and lava flows, ranging in composition from rhyodacite to andesite. A late Miocene granodiorite porphyry stock (8.57 ± 0.49 Ma, U/Pb zircon) intruded into the Eocene sequence. Subvolcanic dykes cut the Eocene rocks and porphyry stock. The Kuh-Panj porphyry system has an extensive and typical hydrothermal alteration zoning pattern, which is comprised of potassic, phyllic, argillic, and propylitic alteration types from inner proximal to outer distal zones. Copper mineralization occurs in potassic and to some extent in phyllic zones. Mineralization is mostly observed as disseminated, stockwork, and vein-veinlets forms in the porphyry stock. Vein paragenesis includes barren quartz, M-type (magnetite+biotite), A1-type (quartz+magnetite+chalcopyrite±chlorite±biotite), A2-type (quartz+chalcopyrite±pyrite), D-type (quartz+pyrite±chalcopyrite), and L-type (galena+sphalerite±chalcopyrite±pyrite) veins. The I-type granitoids with calc-alkaline affinity have enrichments of LILE (Pb, K, U, Sr, and Cs), depletion of HFSE (P, Nb, Ta, Zr, and Ti), and enrichment in LREE displaying geochemical similarity to arc-related magmatic rocks. The high SiO2 (ave. 68.9 wt%), high Al2O3 (ave. 14.5 wt%), low MgO (ave. 1.3 wt%), low P2O5 (< 0.2 wt%), high Sr (ave. 365 ppm), high Sr/Y (ave. 45), relatively high LaN/YbN (ave. 28), relatively high Th (ave. 8 ppm), low Y (ave. 8 ppm), and low Yb (0.5 ppm) contents are similar to those of fertile porphyries and lower crust-derived adakites. The most dominant type of fluid inclusions in quartz from mineralized veins are liquid-vapor-halite-solid (LVHS), liquid-vapor-halite (LVH), liquid-vapor (LV), and vapor-liquid (VL) fluids. Homogenization temperatures of LVHS, LVH, LV, and VL fluids range from 306 to 574 °C, 141–566 °C, 215–422°, and 349–571 °C, respectively. Salinities of LVHS, LVH, LV, and VL fluid inclusions range from 30 to 69, 29.0–65.5, 0.35–22.0, and 0.7–13.0 wt% NaCl eq., respectively. The extreme variations in salinities of fluid inclusions represent the combined effects of varying salinity of the magmatic fluid, aqueous fluid-phase immiscibility (boiling), and mixing with lower salinity meteoric water later in the cooling history of the porphyry system. Normal cooling, water-rock interaction, surface fluid dilution, and boiling are dominant factors that control both the distribution and abundance of mineralization. Zircon from the Kuh-Panj system has high Th/U (0.53 to 0.83), low Dy/Yb (<0.3) ratios, positive Eu/Eu* (1.28–1.85), strong positive Ce/Ce* (1.36 to 197) reflecting high Ce4+/Ce3+ ratios, and enrichment in HREEs relative to LREEs, which indicate the magmatic origin of zircon, oxidized, and hydrous conditions of the primary magma. This magma with adakitic affinities is favorable for producing fertile porphyry systems. Based on these multidisciplinary studies, the Kuh-Panj deposit is classified as a continental arc-related porphyry copper system hosted predominantly at the transition zone between potassic and phyllic alteration zones due to decreasing temperature, boiling, and fluid-rock reaction that all enhance CuFe sulfide saturation.

Effect of Beam Oscillation Amplitude on Microstructure and Mechanical Properties of Small Laser Spot Welded QP980 Steel

In this study, butt welds of QP980 steel were produced using small laser spot (0.1 mm) oscillating welding. The effect of beam oscillation with a circular trajectory on weld morphologies, microstructures, and mechanical properties was characterized. As the oscillating amplitude rose, the energy accumulation range enlarged, and the energy peak value was decreased, leading to the appearance of the cross-section changing from a nail-like shape to a cup-cone-like shape and then to a W-type shape. The weld zone is divided into the fusion zone, inner heat-affected zone, and outer soften zone. The fusion zone and inner heat-affected zone are full of typical lath martensite and have the highest hardness. The soften zone is composed of pre-existing martensite, temper martensite, ferrite, and retained austenite and has the lowest hardness. Compared to laser welding, beam oscillation could reduce the pre-existing block martensite to decompose, leading to a narrower width and higher hardness soften zone. Although the width of the fusion zone and soften zone increases with the oscillation amplitude, all welded samples failed at the base metal with 97% joint efficiency.

Postnatal morpho-functional development of a dog’s meniscus

This study evaluates the morpho-functional modifications that characterize meniscal development from neonatal to adult dogs. Even if menisci are recognized as essential structures for the knee joint, poor information is available about their morphogenesis, in particular in dog models. Menisci from a group of Dobermann Pinchers aged 0, 10, 30 days, and 4 years (T0, T10, T30, adult, respectively) were analyzed by SEM, histochemistry (Safranin O and Picro Sirius Red Staining analyzed under a polarized light microscope), immunofluorescences (collagen type I and II), biomechanical (compression) and biochemical analyses (glycosaminoglycans, GAGs, and DNA content). SEM analyses revealed that the T0 meniscus is a bulgy structure that during growth tends to flatten, firstly in the inner zone (T10) and then even in the outer zone (T30), until the achievement of the completely smooth adult final shape. These results were further supported by the histochemistry analyses in which the deposition of GAGs started from T30, and the presence of type I birefringent collagen fibers was observed from T0 to T30, while poorly refringent type III collagen fibers were observed in the adult dogs. Double immunofluorescence analyses also evidenced that the neonatal meniscus contains mainly type I collagen fibers, as well as the T10 meniscus, and demonstrated a more evident regionalization and crimping in the T30 and adult meniscus. Young's elastic modulus of the meniscus in T0 and T10 animals was lower than the T30 animals, and this last group was also lower than adult ones (T0-T10 vs T30 vs adult). Biochemical analysis confirmed that cellularity decreases over time from neonatal to adult (p < 0.01). The same decreasing trend was observed in GAGs deposition. These results may suggest that the postnatal development of canine meniscus may be related to the progressive functional locomotory development: after birth, the meniscus acquires its functionality over time, through movement, load, and growth itself.

Deep bedrock geothermal resources in the Maichen Sag, Beibuwan Basin and their potential for exploitation and utilization

The Maichen Sag in the south-central part of the Beibuwan Basin is abundant in geothermal resources that have not been widely exploited and utilized due to inadequate research on it. This study evaluated the geothermal resources in the Maichen Sag based on the regional geological setting and geothermal conditions. Grid units for assessment and a geological model for areas with geothermal resources were established using spatial analysis techniques. The spatial distribution models of the physical and thermophysical properties of the geothermal reservoirs were also built using the Kriging interpolation method. Based on the terrestrial heat flow distribution in the target areas, the spatial distribution of the geo-temperature field through the inversion under the constraints of the temperature data from boreholes were predicted. Factors such as deep geo-temperature, thermophysical properties of rocks, and terrestrial heat flow values, were integrated into this quantitative evaluation of geothermal resources through the geological modeling-based volume method and the geothermal reservoir engineering-based numerical simulation method. The results show that the Maichen Sag has favorable heat source conditions with intersected, deep-rooted faults and widely developed Upper Paleozoic fissured granite geothermal reservoirs. The northern outer slope zone at a burial depth of 3‒5 km on the tectonic plane of the basement in the sag is suggested to be a potential target area, where, as calculated using the volume method, is likely to be the home to the total geothermal resources of 80.4×109GJ (i.e., 2.75×109tonnes of coal equivalent (tce)) in the bedrock geothermal reservoirs at a burial depth of 3‒6 km. The geo-temperature of 172‒201°C at a formation depth of 5 km in the sag also indicates that the deep geothermal resources are of high value for exploitation.

Integrating hybrid piezoelectric actuators with a single fiber Bragg grating sensor for online monitoring of structures

The application of fiber Bragg grating (FBG) sensors for detecting ultrasonic guided waves (GW) in a hybrid system with piezoelectric transducers (PZT) is a promising area for structural integrity analysis due to FBG’s potential for embedding in structures. However, the directional sensitivity of FBG sensors presents a challenge for signal processing and the direct application of damage mapping methods designed for omnidirectional PZT sensors is not feasible. The novelty of this study lies in the development of a proof-of-study damage mapping method that uses an improved cosine distance (CD) formulation to detect damage paths while accounting for the directional sensitivity of FBG sensors. Additionally, a sectorial elliptical code (SEC) based on CD was used to localize damages in a hybrid FBG-PZT network. This approach was validated with numerical simulations, demonstrating its effectiveness in accurately detecting and localizing damages in structures. The damage detection with the CD method located all the damage paths which help to identify the probable damage region. The SEC method localized damages not only in the inner sensor zone but also in the outer zone. The CD method successfully predicted the probable damage zones overcoming the directional sensitivity issue. The error predicted with the SEC method was as low as 0.7 cm in the experimental and 0.1 cm in numerical studies.

Effects of fuel-hydrogen levels on combustion, operability, and emission parameters of CH4/H2/O2/CO2 stratified flames in a dual-swirl gas turbine burner

Towards the development of emission-free hydrogen gas turbines with wider operability limits, the combined effects of lean premixed combustion, dual combustion (combustion staging), hydrogen enrichment, and oxy-fuel combustion on the combustion and emission characteristics of CH4/H2/O2/CO2 flames are investigated in a dual annular counter-rotating swirl burner. The central stream is of a higher equivalence ratio (∅) of 0.9 for stable flame ignition, whereas the annular stream is of a lower ∅ of 0.65 to maintain the burner’s environmental performance. The stratified flame reactions are modelled using the partially premixed combustion model, which has been validated using the available experimental data. The inner recirculation zone becomes smaller as the hydrogen fraction (HF) becomes higher until it vanishes and there exists only an outer recirculation zone when the secondary hydrogen fraction approaches 100%. For 100% HF in both primary and secondary flow, the maximum combustion temperature within the combustor was observed to be as high as 2350 K. Increasing HF makes the flame more compact and anchored to the burner centre body with faster kinetics, less ignition delay time, and, accordingly, with increased potential for flashback. The product formation rate was found to increase in the inner shear layer at higher HF, implying a higher flame intensity and a more compact flame. The hydrogen fraction of the primary stream (maintained at higher equivalence ratio) is observed to be dominant in regulating CO mole fractions. Stable well-anchored flames are obtained over the considered fuel mixtures, indicating the role of stratified combustion in widening the operability of gas turbine combustors under stratified combustion conditions.

Experiences with the RTM Method in Local Quasi-Geoid Modeling

In local quasi-geoid modeling, the residual terrain modeling (RTM) method is often used to remove short-wavelength gravity field signals from the measured gravity on the ground in order to obtain a regularized and smooth gravity field that is suited for field interpolation and modeling. Accurate computation of RTM corrections plays a crucial role in computing an accurate local quasi-geoid, and it requires a set of fine-tuned parameters, including the combination of DEMs with different resolutions for suitably representing the real topography, the choice of integration radius for properly defining the extent of the computation zone, and the determination of reference topography to properly describe the RTM-reduced Earth’s surface. To our knowledge, this has not been systematically documented, despite its obvious importance. This study aims to systematically investigate the impact of these factors on RTM correction computation and, consequently, on local quasi-geoid modeling to provide practical guidelines for real-world applications. The tesseroid-based gravity forward modeling technique is employed to investigate the following issues existing in the practical use of the RTM method: ① Can the combination of a high-resolution DEM and a DEM with a lower resolution replace the single use of the high-resolution DEM for RTM correction computation while maintaining accuracy and improving efficiency? If it does, how do I properly choose the resolution of this coarse DEM as well as the integration radius r1 for the inner zone and r2 for the outer zone? ② How large would the differences between the RTM corrections computed by three types of reference topographies, which are obtained from the direct averaging (DA) approach, the moving averaging (MA) approach, and the spherical harmonic (SH) approach, be, and how large would their impact on quasi-geoid modeling be? To obtain objective findings, two research regions were selected for this investigation. One is the Colorado test area (USA) with rugged terrain, and the other is the Auvergne test area (France) with moderate terrain. The main numerical findings are: (1) the combination of the 3” resolution DEM (inner zone) and the 30″ resolution DEM (outer zone) is sufficient for accurate and efficient RTM correction computation; (2) if the resolution of the reference topography is 5′ or slightly lower, all three types of reference topographies are able to obtain local quasi-geoid models at a similar accuracy level, while the values of r1 and r2 are preferred to be at least 20 km and 111 km, respectively; (3) if the reference topography has a resolution of 30′ or lower, the MA or SH reference topography is recommended, especially for the latter one, and the values of r1 and r2 are suggested to be at least 20 km and 222 km, respectively. The above numerical findings can be taken as a reference for local quasi-geoid determination in areas with different topographic regimes than the two selected test areas.

Miocene lamprophyre and felsic volcanics in the outer zone of SW Japan: arc building through multiple sources in an active convergent margin

ABSTRACT Subduction-related magmatism is a significant contributor to arc building and continental growth. In the active convergent margin of the SW Japan arc, voluminous volcanic rocks and mafic dykes formed through subduction and back-arc rifting during Miocene. In this study, we investigate a suite of felsic volcanic rocks (rhyolite and dacite) and lamprophyres from central Shikoku Island, which occur in the north-central part of the Chichibu belt and Sanbagawa belt in the Outer zone of the SW Japan arc. Whole-rock geochemistry results show that the rhyolite and dacite samples are peraluminous, belong to the high-K calc-alkaline series, show LREE and LILE enrichment, HREE and HFSE depletion that suggest arc volcanic affinity. The lamprophyre samples belong to alkali lamprophyre, show LREE and HFSE enrichments, and display OIB (oceanic island basalt)-like geochemical features. The 206Pb/238U weighted mean ages of the zircons from the rhyolite and dacite samples range from 14.39 ± 0.21 Ma to 13.92 ± 0.30 Ma, whereas the lamprophyre shows 206Pb/238U weighted mean age of 12.21 ± 0.35 Ma. Zircon Lu-Hf isotope data suggest that the rhyolite and dacite were derived from the remelting of the arc crustal rocks and that the lamprophyre was derived from depleted mantle sources and was contaminated by crustal materials. The felsic volcanic rocks (rhyolite and dacite) can be correlated to Miocene (15.5 Ma to 13.5 Ma) magmatism in the Outer Zone of the SW Japan arc. The formation of lamprophyre dykes in the SW Japan arc may be related to the subhorizontal mantle flows beneath the SW Japan arc associated with the opening of the Japan Sea back-arc basin or asthenosphere upwelling through the slab-tear of the Philippine Sea Plate beneath the SW Japan arc. Our study shows that the SW Japan Arc was built by multiple magmatism from diverse sources in an active convergent margin.

Constraining mixing and mingling processes from zoned magmatic enclaves: An example from the Taejongdae granite in Busan, Korea

Zoned magmatic enclaves (MEs) within granitic intrusions provide valuable insights into the pre-intrusive processes involved in the formation of granitic magmas. This study focuses on the Taejongdae granite in Busan, Korea, which features uniquely zoned MEs, and aims to constrain the processes involved in their formation. Through a whole-rock geochemistry analysis, SHRIMP U-Pb zircon dating, and Lu-Hf isotope data, we investigated the geochemical characteristics and origin of the two magmas responsible for the zoned MEs (that is, dioritic and host granite magmas). Our findings have shown that the host granite aligns with the Bulguksa granites in the Gyeongsang Basin, which represent the I-Type magma resulting from the fractionation of magma generated through partial melting of the continental crust. In contrast, the dioritic magma exhibits a low K2O composition, high Sr content, and a positive-to-no Eu anomaly, indicating its formation via amphibole-dominated fractional crystallization under different pressure–temperature conditions. Both magmas share the same Cretaceous age and Hf ratios. The zoned MEs in the study area provide compelling evidence of magma mixing processes that occur between the outer dioritic zone and mafic core of the enclaves. However, the relationship between the outer dioritic zone and the host granite suggests limited interaction between the enclaves and host granite. This implies that mixing within the zoned enclaves occurred prior to enclosure in the host granite. By highlighting the significance of zoned magmatic enclaves, this case study advances our understanding of the pre-intrusive processes involved in the formation of granitic magmas, including magmatic mixing, mingling, and fractionation. These results offer important insights into the origin and geochemical characteristics of the two magmas and their interactions, thus contributing to a broader understanding of crustal evolution in subduction-related settings.