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Nanometer‐scale titanomagnetite crystals have been detected in nominally aphyric rhyolite pumice, but whether they are numerous enough to impact bubble nucleation in explosive silicic volcanism was unresolved. This study examines sub‐micron crystals using rock magnetic techniques, Rhyolite‐MELTS modeling, and physical characterization. We analyzed pumice from four eruptions spanning wide ranges in intensity, storage depth, and bubble number density (1016 to 1013 m−3 liquid): 1060 CE Glass Mountain, 1912 CE Novarupta, 232 CE Taupo, and 0.45 Ma Pudahuel. Calculations assuming monospecific assemblages of 10 and 1,000 nm cubic particles yield titanomagnetite number densities of 1021 to 1013 m−3 dense rock equivalent, respectively. In all cases, titanomagnetite is thermodynamically stable at pre‐eruptive storage conditions and magnetic susceptibility (χLF) is independent of vesicularity and permeability, indicating that crystals likely formed prior to vesiculation. The existence of nm‐scale Fe‐Ti oxides in four diverse cases suggests that heterogeneous bubble nucleation is a general feature of explosive rhyolite volcanism.

Recently, concerns have increased regarding the presence of antibiotics in water resources. This increase has been caused by the discharge of untreated or incompletely treated pharmaceutical wastewater into aquatic environments. Metronidazole is a widely used antibiotic for the treatment of infections caused by anaerobic bacteria and protozoa. The present study investigated the efficacy of nano-pumice prepared from pumice mine waste as a low-cost adsorbent for metronidazole removal from aqueous environments. The effects of input variables, including pH, contact time, nano-pumice dose, and metronidazole concentration, were investigated. The experimental design was based on central point’s using the response surface method to study adsorption. After optimizing the input variables, isotherm and kinetic studies were conducted. The properties of the adsorbent were characterized through FESEM, XRD, BET, and FTIR analyses. The results indicated that the adsorption process followed a quadratic polynomial model, with F and p values of 990.936 and less than 0.0001, respectively. Additionally, the R 2 was 0.9989, and the Adj-R 2 was 0.9979. The optimal conditions for achieving a removal efficiency of 94.55% and maximum adsorption capacity of 15.313 mg/g were found to be pH = 3, contact time = 60 min, adsorbent dose = 1.5 g/L, and metronidazole concentration = 20 mg/L. Furthermore, the adsorption process aligned with the Langmuir isotherm and pseudo-first-order kinetics, as indicated by R 2 values of 0.9965 and 0.9859, respectively. Therefore, nano-pumice can be suggested as a natural and environmentally friendly adsorbent with significant potential for the adsorption of metronidazole and similar antibiotics from aqueous media. Graphical abstract

Low-density cement slurry is essential for addressing cementing challenges in low-pressure, permeable formations. In response to the issues of poor shear stability, susceptibility to breakage, and unstable density in traditional pumice low-density cement slurries, a solid composite microsphere low-density weight reducer CMA was used in the laboratory to improve cementing quality and address the cement slurry leakage problem in low-pressure, easy-to-leak wells. A low-density cement slurry system with solid composite microspheres was developed. Experimental results show that this low-density cement slurry system has good sedimentation stability, low fluid loss, strong pressure resistance, and good density stability under high-speed shear conditions. The application was carried out at Well CH2, solving the cementing leakage problem of Well CH2, with a 100% qualified rate for cementing quality, achieving good construction results.

Since there is a deficit of raw materials available for construction, concrete is essential in designing concrete structures in the modern world. As a result, the construction sector is now familiar with cutting-edge techniques that utilize waste material that is readily available for partial replacement by substituting alternative aggregates for regular aggregates. In this study, pumice stone located in the lowest section of the ocean or the abyss of red clay is utilized in place of concrete, with a replacement in a portion made of pumice mixed with cement. Concrete’s mechanical and physical durability was examined by measuring its Split and compressive strengths of ordinary concrete and substituting it with varying quantities of pumice (10% to 30%). M sand is entirely replaced in fine aggregate. From the previous studies, it shows the 50% of Coarse aggregate replacement and here we investigate how well partial pumice substitutions for coarse aggregate and M sand substitutions of fine aggregate can gain sufficient strength. Based on the experimental results, the current thesis compares the properties of conventional and replaced concrete for the various percentages of pumice stone replacement to coarse aggregate. It concludes that a 25% partial replacement by pumice yields the maximum compressive strength. We also studied the durability parameters in the present paper.

This study compares the workability, mechanical, and thermal characteristics of structural self-compacting lightweight concrete (SCLWC) formulations using pumice aggregate (PA), expanded perlite aggregate (EPA), fly ash (FA), and silica fume (SF). FA and SF were used as partial substitutes for cement at a 10% ratio in various mixes, impacting different aspects: According to the obtained results, FA enhanced the workability but SF reduced it, while SF improved the compressive and splitting tensile strengths more than FA. EPA, used as a fine aggregate alongside PA, decreased the workability, compressive strength, and splitting tensile strength compared to the control mix (K0). The thermal properties were altered by FA and SF similarly, while EPA notably reduced the thermal conductivity coefficients. The thermal conductivity coefficients (TCCs) of the K0–K4 SCLWC mixtures ranged from 0.275 to 0.364 W/mK. K0 had a TCC of 0.364 W/mK. With 10% FA, K1 achieved 0.305 W/mK; K2 with 10% SF reached 0.325 W/mK. K3 and K4, using EPA instead of PA, showed significantly lower TCC values: 0.275 W/mK and 0.289 W/mK, respectively. FA and SF improved the thermal conductivity compared to K0, while EPA further reduced the TCC values in K3 and K4 compared to K1 and K2. The compressive strength (CS) values of the K0–K4 SCLWC mixtures at 7 and 28 days reveal notable trends. Using 10% FA in K1 decreased the CS at both 7 days (12.16 MPa) and 28 days (22.36 MPa), attributed to FA’s gradual pozzolanic activity. Conversely, K2 with SF showed increased CS at 7 days (17.88 MPa) and 28 days (29.89 MPa) due to SF’s rapid pozzolanic activity. Incorporating EPA into K3 and K4 reduced the CS values compared to PA, indicating EPA’s lower strength contribution due to its porous structure.

This study evaluated the possibilities of pumice (light stones) as litter material in broiler production. Experimental treatments included wood shavings (WS), acidic pumice (AP), and basic pumice (BP) alone, and in combination; wood shaving + acidic pumice (WSAP) and wood shaving + basic pumice (WSBP) in a ratio of 1:1. Two trials were performed, one in summer, and the other in winter. Each trial involved 750 mixed-sex Ross (308) broilers. Also, there were 15 replicate pens with 50 broilers and a stocking density of 12.5 birds/m 2 for each pen at the beginning of each trial. Performance, litter quality, carcass parameters, body and leg abnormalities, body temperature, fear and stress responses, proportional asymmetry, and some behavior expressions were investigated. The litter treatment influenced the final live body weight, litter moisture, ammonia concentration, footpad dermatitis, hock burn, breast blister, hot carcass yield, heart, liver, spleen, abdominal fat, wing and neck ratio, breast and back cleanliness, and the expression of dust bathing and foraging behaviors ( P  < 0.01; P  < 0.05). Furthermore, there was a seasonal effect on live body weight, feed conversion ratio, livability, litter pH, 42-day litter moisture, hot carcass yield, back cleanliness, footpad dermatitis, hock burn, footpad temperature, heterophil-to-lymphocyte ratio, and expression of pecking behavior ( P  < 0.01; P  < 0.05). It is suggested that acidic pumice stone alone or in a mixture with wood shavings could be used as a reliable litter material, alternative to wood shavings.

The presence of mafic enclaves and banded pumice reveals key physical processes associated with volcanic eruptions. Here, through the textural and geochemical analyses of the 3550 B.P. Waimihia deposits in Taupō, New Zealand, we demonstrate how disequilibrium crystallization controls the way magmas mix. Andesitic enclaves in pyroclastic deposits from this predominantly rhyolitic eruption consist of microlites that crystallized rapidly during mafic injection into rhyolitic host magma. The variation of microlite textures depends on enclave size, implying that mafic enclaves crystallized as discrete blobs within a host rhyolitic magma. However, gray pumice and dark bands in banded pumice are characterized by a lack of or less plagioclase microlites that should be present if equilibrium crystallization occurred. Our textural and chemical data suggest that the lack of plagioclase in gray pumice and dark bands resulted from the nucleation delay arising from the mixing with rhyolitic magma. After mafic magma broke up in a magma chamber as discrete mafic blobs, the plagioclase-free rim of the blobs was disaggregated by shear flow. The eroded mafic blobs form a hybrid magma by mixing with rhyolitic magma, which further delays the plagioclase nucleation. This hybrid magma eventually erupted as gray pumice or banded pumice, depending on the intensity of magma mingling in the conduit. We use a plagioclase nucleation delay model to calculate residence times of hours to tens of hours prior to eruption. Our mixing model with nucleation delay enables small volumes of mafic magma to mix with large amounts of silicic magma.

The trachydacitic Alpehué tephra from Sollipulli volcano (Andean Southern Volcanic Zone), consists of ignimbrite and fallout from a Plinian eruption about 3000 years ago. It is mainly composed of (1) crystal-rich pumice and ash but also contains (2) chilled knobbly basaltic lava clasts and (3) mostly highly inflated glomerocrystic fragments with high crystal-glass ratios interpreted to represent a crystal mush zoned from basaltic to dacitic bulk compositions. Knobbly lava clasts are of three types: (a) a very phenocryst-poor basalt, (b) a basalt with large, unzoned olivine and plagioclase phenocrysts and glomerocrysts, and (c) mixtures of microcrystalline basalt with various fragments, glomerocrysts and crystals derived from a crystal mush. Clast type (4) in the tephra is banded pumices in which the three magmatic components occur variably mingled. Thermobarometry and petrographic observations, particularly presence or absence of amphibole, constrain an upper-crustal succession of a lower basaltic reservoir, a zoned basaltic to dacitic crystal mush reservoir, and a separate trachydacite magma chamber on top. All Alpehué magmatic components form a coherent liquid line of descent which supports the interpretation that the crystal mush reservoir is a gradually solidifying magma chamber, not the result of large-scale crystal-liquid segregation. The trachydacite magma may originally have formed as melt escaping from the crystal-mush reservoir but subsequently underwent a long and complex evolution recorded in large strongly zoned plagioclase phenocrysts including resorption horizons. The ascending mafic magmas collected samples from the crystal mush body and intruded the trachydacite reservoir. The phenocryst-poor basalt (a) arrived first and entrained and partially resorbed plagioclase from the host magma. The phyric basalt (b) arrived later and did not resorb entrained plagioclase before eruption. Estimated cooling times, plagioclase resorption times and ascent rates avoiding amphibole breakdown limit the duration of these pre-eruptive processes to not more than a few days.

Internal curing might be considered crucial for applications, where High-Performance Concrete (HPC) mixtures are needed, to mitigate or even eliminate the development of autogenous shrinkage and thus the formation of early-age microcracks that diminish the durability of concrete. Lightweight aggregates act as a water reservoir that provides water to unhydrated cement particles when needed, has already been proven an effective curing mechanism. On the other hand, adding supplementary cementitious materials could be a subsidiary strategy to prevent autogenous shrinkage, although in some cases opposite results were reported. Even though metakaolin is well known for its pozzolanic activity and contribution to enhancing concrete’s mechanical and durability properties, its effect on autogenous shrinkage needs further investigation. This research examines the individual effects of pumice and metakaolin, as well as their combined influence on autogenous and drying shrinkage. The findings indicate that while metakaolin slightly increases early-age shrinkage, it contributes to a reduction in drying shrinkage at later stages.

This study addresses the problem of pumice deposits in the southern Kyushu region, which can cause landslides during heavy rainfall. To reduce this hazard, it is important to expand pumice applications and promote its use before disaster events occur. Among construction materials, this study explores the possibility of using pumice as a concrete aggregate, considering the global shortage of natural aggregates. Because of the low strength and difficulty of use, pumice must be fired to improve its properties. In our experiment, it was fired at 1000 or 1100 °C, and the performance of the resulting concretes was compared. Concrete incorporating pumice fired at 1100 °C achieved a maximum compressive strength of 54.6 N/mm2 with an increase in the amount of cement, whereas concrete with pumice fired at 1000 °C remained within the 20–24 N/mm2 range even when the amount of cement was increased. This difference arises because pumice has a lower strength than the cement paste, leading to material failure. Furthermore, freeze–thaw tests showed that concrete made with pumice fired at 1100 °C was resistant to frost damage. These results suggest that pumice fired at 1100 °C has an excellent potential as a sustainable building material.