Advanced materials engineering in historical gypsum plaster formulations.

We show how historical gypsum plaster preparation methods affect the microstructure and the wettability properties of the final stucco materials. We reproduced a traditional Persian recipe (Gach-e Koshteh, ~14th century AD), which involves a continuous mechanical treatment during plaster hydration. These samples were compared with a laboratory-replicated historical recipe from Renaissance Italy (Gesso Sottile, ~15th century AD) and contemporary low-strength plaster. The Koshteh recipe induces the formation of gypsum platelets, which exhibit preferential orientation in the plaster bulk. In contrast, the Italian and low-strength plasters comprise a typical needle-like morphology of gypsum crystals. The platelets in Koshteh expose the more hydrophilic {010} face of gypsum in a much more pronounced manner than needles. Consequently, the Iranian plaster displays enhanced wettability, enabling its direct use for water-based decoration purposes, or as a fine finishing thin layer, without the need of mixing it with a binder material. Contrary, in Sottile, gypsum crystals are left to equilibrate in large excess of water, which promotes the growth of long needles at the expense of smaller crystals. Typically, such needles are several times longer than those found in a control regular plaster. For this crystal habit, the total surface of hydrophilic faces is minimized. Consequently, such plaster layers tend to repel water, which can then be used, e.g., as a substrate for oil-based panel paintings. These findings highlight the development of advanced functional materials, by tuning their microtexture, already during the premodern era.

Godanti bhasma (anhydrous CaSO4) induces massive cytoplasmic vacuolation in mammalian cells: A model for phagocytosis assay.

Phagocytosis is an essential physiological mechanism; its impairment is associated with many diseases. A highly smart particle is required for understanding detailed sequential cellular events in phagocytosis. Recently, we identified an Indian traditional medicine named Godanti Bhasma (GB), a bioactive calcium sulfate particle prepared by thermo-transformation ofgypsum. Thermal processing of the gypsum transforms its native physicochemical properties by removing water molecules into the anhydrous GB, which was confirmed by Raman and FT-IR spectroscopy. GB particle showed a 0.5-5 µm size range and a neutral surface charge. Exposure of mammalian cells to GB particles showed a rapid cellular uptake through phagocytosis and induced massive cytoplasmic vacuolation in cells. Interestingly, no cellular uptake and cytoplasmic vacuolation were observed with the parent gypsum particle. The presence of the GB particles in intra-vacuolar space was confirmed using FESEM coupled with EDX. Flow cytometry analysis and live tracking of GB-treated cells showed particle internalization, vacuole formation, particle dissolution, and later vacuolar turnover. Quantification of GB-induced vacuolation was done using neutral red uptake assay in cells. Treatment of lysosomal inhibitors (BFA1 or CQ) with GB could not induce vacuolation, suggesting the requirement of an acidic environment for the vacuolation. In the mimicking experiment, GB particle dissolution in acidic cell-free solution suggested that degradation of GB occurs by acidic pH inside the cell vacuole. Vacuole formation generally accompanies with cell death, whereas GB-induced massive vacuolation does not cause cell death. Moreover, the cell divides and proliferates with the vacuolar process, intra-vacuolar cargo degradation, and eventually vacuolar turnover. Taken together, the sequential cellular events in this study suggest that GB can be used as a smart particle for phagocytosis assay development in animal cells.

Nutritional convergence in plants growing on gypsum soils in two distinct climatic regions.

BACKGROUND AND AIMS: Soil endemics have long fascinated botanists due to the insights they can provide about plant ecology and evolution. Often, these species have unique foliar nutrient composition patterns that reflect potential physiological adaptations to these harsh soil types. However, understanding global nutritional patterns to unique soil types can be complicated by the influence of recent and ancient evolutionary events. Our goal was to understand whether plant specialization to unique soils is a stronger determinant of plant nutrient composition than climate or evolutionary constraints. METHODS: We worked on gypsum soils. We analyzed whole-plant nutrient composition (leaves, stems, coarse roots and fine roots) of 36 native species of gypsophilous lineages from the Chihuahuan Desert (North America) and the Iberian Peninsula (Europe) regions, including widely distributed gypsum endemics, as specialists, and narrowly distributed endemics and non-endemics, as non-specialists. We evaluated the impact of evolutionary events and soil composition on the whole-plant composition, comparing the three categories of gypsum plants. KEY RESULTS: Our findings reveal nutritional convergence of widely distributed gypsum endemics. These taxa displayed higher foliar Sulfur and higher whole-plant Magnesium than their non-endemic relatives, irrespective of geographic location or phylogenetic history. Sulfur and Magnesium concentrations were mainly explained by non-phylogenetic variation among species related to gypsum specialization. Other nutrient concentrations were determined by more ancient evolutionary events. For example, Caryophyllales usually displayed high foliar Calcium, whereas Poaceae did not. In contrast, plant concentrations of Phosphorus was mainly explained by species-specific physiology not related to gypsum specialization or evolutionary constraints. CONCLUSIONS: Plant specialization to a unique soil may strongly influence plant nutritional strategies, as we described for gypsophilous lineages. Taking a whole-plant perspective (all organs) within a phylogenetic framework has enabled us to gain a better understanding of plant adaptation to unique soils when studying taxa from distinct regions.

Comparative analysis of cyanobacterial communities in gypsum outcrops: insights from sites in Israel and Poland.

Today, the biodiversity of endolithic microbial colonisations are only partly understood. In this study, we used a combination of molecular community metabarcoding using the 16S rRNA gene, light microscopy, CT-scan analysis, and Raman spectroscopy to describe gypsum endolithic communities in 2 sites-southern Poland and northern Israel. The obtained results have shown that despite different geographical areas, climatic conditions, and also physical features of colonized gypsum outcrops, both of these sites have remarkably similar microbial and pigment compositions. Cyanobacteria dominate both of the gypsum habitats, followed by Chloroflexi and Pseudomonadota. Among cyanobacteria, Thermosynechococcaceae were more abundant in Israel while Chroococcidiopsidaceae in Poland. Interestingly, no Gloeobacteraceae sequences have been found in Poland, only in Israel. Some of the obtained 16S rRNA gene sequences of cyanobacteria matched previously detected sequences from endolithic communities in various substrates and geographical regions, supporting the hypothesis of global metacommunity, but more data are still needed. Using Raman spectroscopy, cyanobacterial UV-screening pigments-scytonemin and gloeocapsin have been detected alongside carotenoids, chlorophyll a and melanin. These pigments can serve as potential biomarkers for basic taxonomic identification of cyanobacteria. Overall, this study provides more insight into the diversity of cyanobacterial endolithic colonisations in gypsum across different areas.

Gypsum Cave Biofilm Communities are Strongly Influenced by Bat- And Arthropod-Related Fungi.

The Gypsum Karst of Sorbas, Almeria, southeast Spain, includes a few caves whose entrances are open and allow the entry and roosting of numerous bats. Caves are characterized by their diversity of gypsum speleothems, such as stalactites, coralloids, gypsum crusts, etc. Colored biofilms can be observed on the walls of most caves, among which the Covadura and C3 caves were studied. The objective was to determine the influence that bat mycobiomes may have on the fungal communities of biofilms. The results indicate that the fungi retrieved from white and yellow biofilms in Covadura Cave (Ascomycota, Mortierellomycota, Basidiomycota) showed a wide diversity, depending on their location, and were highly influenced by the bat population, the guano and the arthropods that thrive in the guano, while C3 Cave was more strongly influenced by soil- and arthropod-related fungi (Ascomycota, Mortierellomycota), due to the absence of roosting bats.

Ultrafast and highly efficient Cd(II) and Pb(II) removal by magnetic adsorbents derived from gypsum and corncob: Performances and mechanisms.

The utilization of gypsum and biomass in environmental remediation has become a novel approach to promote waste recycling. Generally, raw waste materials exhibit limited adsorption capacity for heavy metal ions (HMIs) and often result in poor solid-liquid separation. In this study, through co-pyrolysis with corncob waste, titanium gypsum (TiG) was transformed into magnetic adsorbents (GCx, where x denotes the proportion of corncob in the gypsum-corncob mixture) for the removal of Cd(II) and Pb(II). GC10, the optimal adsorbent, which was composed primarily of anhydrite, calcium sulfide, and magnetic Fe3O4, exhibited significantly faster adsorption kinetics (rate constant k1 was 218 times and 9 times of raw TiG for Cd(II) and Pb(II)) and higher adsorption capacity (Qe exceeded 200 mg/g for Cd(II) and 400 mg/g for Pb(II)) than raw TiG and previous adsorbents. Cd(II) removal was more profoundly inhibited in a Cd(II) + Pb(II) binary system, suggesting that GC10 showed better selectivity for Pb(II). Moreover, GC10 could be easily separated from purified water for further recovery, due to its high saturation magnetization value (6.3 emu/g). The superior removal capabilities of GC10 were due to adsorption and surface precipitation of metal sulfides and metal sulfates on the adsorbent surface. Overall, these waste-derived magnetic adsorbents provide a novel and sustainable approach to waste recycling and the deep purification of multiple HMIs.

Characteristics of Micro-Seismic Events Induced by Ground Collapse-A Case Study in the Rongxing Gypsum Mine in Hubei Province, China.

Mining activities can damage rock masses and easily induce ground collapse, which seriously threatens safe production in mining areas. Micro-seismic systems can monitor rock mass deformation signals in real time and provide more accurate data for rock mass deformation analysis. Therefore, in this study, the waveform characteristics of micro-seismic events induced by ground collapse in the Rongxing gypsum mine were analyzed; the occurrence of these events was introduced on the basis of Fast Fourier Transform, an established Frequency-Time-Amplitude model, in order to put forward the index of energy proportion of the main band. The results showed the following. (1) The seismic sequence type of ground collapse was foreshock-mainshock-aftershocks. The interval between the foreshock and mainshock was longer than that between the mainshock and aftershocks. (2) The deformation corresponding to the foreshock micro-seismic events was mainly that of a small-scale crack. The deformation corresponding to the micro-seismic events during the mainshock was characterized by the gradual development of small-scale cracks, and the development of large-scale cracks accelerated, accompanied by slight rock collapse. The deformation corresponding to the micro-seismic events during the aftershocks showed that almost no small-scale cracks developed, and the large-scale crack development was intense, and accompanied by numerous rock and soil mass collapses. (3) The observed decreasing frequency distribution and energy dispersion can be used as possible precursors of ground collapse.

Effect of Fiber Loading on Mechanical and Flame-Retardant Properties of Poplar-Fiber-Reinforced Gypsum Composites.

Gypsum-based composites were prepared via a slurry casting process using construction gypsum as the binding material and poplar fibers as reinforcing material. The effects of different fiber content and curing time on the mechanical properties, water resistance, and flame retardancy of these composites were investigated, and the influence mechanism was characterized by infrared spectroscopy, scanning electron microscopy, and X-ray diffractometry. The results showed that the best composite mechanical strength was achieved with 10% poplar fiber- content, and the absolute dry flexural and compressive strengths reached 3.59 and 8.06 MPa, respectively. Compared with pure gypsum, the flexural strength and compressive strength increased by 10% and 19%, respectively. The inclusion of fibers somewhat prevented the migration of free water within the composites and enhanced their water resistance. At 10% fiber content, the composite's 24 h water absorption rate was 34.3%, 8% lower than that of pure gypsum, with a softening coefficient of 0.55. However, fiber content increases the porosity of gypsum-based composites. When heated, this increased porosity accelerates' heat conduction within the matrix, raising the peak and total exothermic rates, thereby weakening the composites' inherently flame-retardant properties. Poplar-fiber-reinforced gypsum-based composites offered superior performance in commercial applications, compared to pure gypsum board, providing a sustainable and green alternative for ceilings, partitions, and other applications, while broadening the prospects for gypsum-based composites in the engineering field.

High-strength gypsum binder with improved water-resistance coefficient derived from industrial wastes.

The article presents the possibility of increasing the water resistance of gypsum binders (GBs) obtained based on synthetic gypsum by introducing additives derived from industrial wastes. Regularities were obtained for the influence of the type and amount of additives on the water/gypsum ratio (W/G), strength indicators and water resistance of high-strength GB. The introduction of a single-component additive to improve water resistance does not have a significant effect. Complex additives based on Portland cement, granulated blast-furnace slag, electric steel-smelting slag, expanded clay dust and granite screenings of various fractions have been developed that make the maximum contribution to improving the water resistance of a high-strength GB based on synthetic calcium sulphate dihydrate, which made it possible to increase the water-resistance coefficient from 0.39 to 0.82.

[Research progress in pharmacological effects of Gypsum Fibrosum and material basis for its heat-clearing effect].

Gypsum Fibrosum, as a classic heat-clearing medicine, is widely used in the clinical practice of traditional Chinese medicine(TCM). However, debates exist about the material basis and mechanism of its efficacy. Therefore, this paper reviewed the recent research progress in the heat-clearing effect and mechanism of Gypsum Fibrosum and discussed the material basis for the heat-clearing effect of this medicine. Ca~(2+) may inhibit the upward movement of temperature set point by regulating the Na~+/Ca~(2+) level in the heat-regulating center. Moreover, trace elements may inhibit the rise of body temperature by regulating the immune system, promoting the absorption of Ca~(2+), and affecting the synthesis of prostaglandin E2(PGE2). This review aims to enrich the knowledge about the mechanism of Gypsum Fibrosum in clearing heat and provides a scientific basis for the clinical application and further development of Gypsum Fibrosum.

Nitrogen transfer between plant species with different temporal N-demand.

Phenological segregation among species in a community is assumed to promote coexistence, as using resources at different times reduces competition. However, other unexplored nonalternative mechanisms can also result in a similar outcome. This study first tests whether plants can redistribute nitrogen (N) among them based on their nutritional temporal demand (i.e. phenology). Field 15 N labelling experiments showed that 15 N is transferred between neighbour plants, mainly from low N-demand (late flowering species, not reproducing yet) to high N-demand plants (early flowering species, currently flowering-fruiting). This can reduce species' dependence on pulses of water availability, and avoid soil N loss through leaching, having relevant implications in the structuring of plant communities and ecosystem functioning. Considering that species phenological segregation is a pervasive pattern in plant communities, this can be a so far unnoticed, but widely spread, ecological process that can predict N fluxes among species in natural communities, and therefore impact our current understanding of community ecology and ecosystem functioning.

Dryland endolithic Chroococcidiopsis and temperate fresh water Synechocystis have distinct membrane lipid and photosynthesis acclimation strategies upon desiccation and temperature increase.

An effect of climate change is the expansion of drylands in temperate regions, predicted to affect microbial biodiversity. Photosynthetic organisms being at the base of ecosystem's trophic networks, we compared an endolithic desiccation-tolerant Chroococcidiopsis cyanobacteria isolated from gypsum rocks in the Atacama Desert, with a freshwater desiccation-sensitive Synechocystis. We sought whether some acclimation traits in response to desiccation and temperature variations were shared, to evaluate the potential of temperate species to possibly become resilient to future arid conditions. When temperature varies, Synechocystis tunes the acyl composition of its lipids, via a homeoviscuous acclimation mechanism known to adjust membrane fluidity, whereas no such change occurs in Chroococcidiopsis. Vice versa, a combined study of photosynthesis and pigment content shows that Chroococcidiopsis remodels its photosynthesis components and keeps an optimal photosynthetic capacity at all temperatures, whereas Synechocystis is unable to such adjustment. Upon desiccation on a gypsum surface, Synechocystis is rapidly unable to revive, whereas Chroococcidiopsis is capable to recover after three weeks. Using X-ray diffraction, we found no evidence that Chroococcidiopsis could use water extracted from gypsum crystal in such conditions, as a surrogate of missing water. The sulfolipid sulfoquinovosyldiacylglycerol becomes the prominent membrane lipid in both dehydrated cyanobacteria, highlighting an overlooked function for this lipid. Chroococcidiopsis keeps a minimal level of monogalactosyldiacylglycerol, which may be essential for the recovery process. Results support that two independent adaptation strategies have evolved in these species to cope with temperature and desiccation increase, and suggest some possible scenarios for microbial biodiversity change triggered by climate change.

Paleoenvironments represented by the sediments of the Early Pliocene Mursi Formation, Omo Valley, Ethiopia.

While our understanding of human origins has been enriched by extensive efforts to reconstruct the ancient environmental context of early hominins using information from hominin-bearing localities, comparatively little effort has been focused on contemporaneous fossil localities with abundant vertebrate fossils, but lacking hominins. We report here on new paleoenvironmental reconstructions of the Mursi Formation, Ethiopia, from which strata dated to >4 Ma preserve an abundant vertebrate fossil record lacking any known hominins, despite being part of a contiguous sedimentary basin known for its rich hominin fossil record. We combine new stratigraphic and sedimentological observations with data from paleosols preserved in the sedimentary sequence, along with isotopic data from pedogenic carbonate, paleosol organic matter, and sulfur minerals preserved in the sediments (gypsum, native sulfur). Paleosol features and carbon isotopic composition of fossil organic matter and pedogenic carbonate complement data from the mammalian fauna, the sum of which provide evidence of closed woodland to forest vegetation. Sedimentological data indicate that these wooded terrestrial habitats occurred near aquatic settings characterized by stagnant shallow waters of a freshwater lake, providing a reconstruction of unique habitats in contrast with hominin localities >4 Ma.

Albertania and Egbenema gen. nov. from Nigeria and the United States, expanding biodiversity in the Oculatellaceae (cyanobacteria).

Knowledge of the tropical terrestrial cyanobacterial flora from the African continent is still limited. Of 31 strains isolated from soil and subaerial samples collected in Lagos State, Nigeria, three were found to be in the Oculatellaceae, including two species in a new genus. Subsequently, isolates from microbial mats in White Sands National Park in New Mexico, United States, and from a rock near the ocean in Puerto Rico, United States, were found to belong to the new genus as well. Cyanobacterial isolates were characterized microscopically, sequenced for the 16S rRNA gene and associated ITS region, and phylogenetically analyzed. Egbenema gen. nov., with three new species, as well as two new species of Albertania were differentiated from all other Oculatellaceae. Both genera belong to a supported clade within the Oculatellaceae that includes Trichotorquatus and Komarkovaea. The two new species of Albertania, A. egbensis and A. latericola, were from the same sample, but were evolutionarily separate based on 16S rRNA gene phylogenies, percent identity below the 98.7% threshold, and ITS rRNA percent dissimilarity >7.0%. Egbenema aeruginosum gen. et sp. nov. was phylogenetically separated from Trichotorquatus and Albertania but was in a clade with other strains belonging to Egbenema. The two Egbenema strains from the United States are here named Egbenema epilithicum sp. nov. and Egbenema gypsiphilum sp. nov. Our results support the hypothesis that further species discoveries of novel cyanobacteria will likely be made in soils and subaerial habitats, as these habitats continue to be studied, both in tropical and temperate biomes.

Enzyme activities and organic matter mineralization in response to application of gypsum, manure and rice straw in saline and sodic soils.

Saline and alkaline soils are a challenge for sustainable crop production. The use of organic and inorganic amendments is a common practice to increase the fertility of salt-affected soils that can trigger faster carbon (C) and nitrogen (N) cycling. We examined the effects of gypsum (Gyps), farm manure (Manure) and rice straw (Straw) on enzyme activities, organic matter mineralization and CO2 emissions in two salt-affected soils [Solonchak (saline); pH: 8, electrical conductivity (EC): 6.5, sodium adsorption ratio (SAR): 2.5, and Solonetz (alkaline sodic); pH: 8.9, EC: 1.6, SAR: 17]. Gypsum addition decreased soil pH up to 0.62 and 0.30 units, SAR 1.2 and 5.2 units, and EC 2.9 and 1.4 units in Solonchak and Solonetz, respectively. Dissolved organic C, microbial biomass C, dissolved organic N, mineral N (NO3- and NH4+), enzyme activities (urease, invertase, catalase, phosphatase, phenol-oxidase), alkali extractable phenols, and available phosphorous increased with the application of all amendments in both soils. Solonetz released more CO2 than Solonchak, whereas maximum CO2 emissions were common after manure application (3140 mg kg-1 in Solonchak, and 3890 mg kg-1 in Solonetz). We conclude that high SAR and low EC increase CO2 emissions through accelerated C and N cycling and manure decomposition in Solonetz soils.

Mechanism of water extraction from gypsum rock by desert colonizing microorganisms.

Microorganisms, in the most hyperarid deserts around the world, inhabit the inside of rocks as a survival strategy. Water is essential for life, and the ability of a rock substrate to retain water is essential for its habitability. Here we report the mechanism by which gypsum rocks from the Atacama Desert, Chile, provide water for its colonizing microorganisms. We show that the microorganisms can extract water of crystallization (i.e., structurally ordered) from the rock, inducing a phase transformation from gypsum (CaSO4·2H2O) to anhydrite (CaSO4). To investigate and validate the water extraction and phase transformation mechanisms found in the natural geological environment, we cultivated a cyanobacterium isolate on gypsum rock samples under controlled conditions. We found that the cyanobacteria attached onto high surface energy crystal planes ({011}) of gypsum samples generate a thin biofilm that induced mineral dissolution accompanied by water extraction. This process led to a phase transformation to an anhydrous calcium sulfate, anhydrite, which was formed via reprecipitation and subsequent attachment and alignment of nanocrystals. Results in this work not only shed light on how microorganisms can obtain water under severe xeric conditions but also provide insights into potential life in even more extreme environments, such as Mars, as well as offering strategies for advanced water storage methods.

Emplacement and associated sedimentary record of the Jurassic submarine salt allochthon of the Wurzeralm (Eastern Alps, Austria).

A fossil salt sheet emplaced in the Jurassic in submarine conditions is described in the Eastern Alps of Austria, providing unique insights into the emplacement of similar submarine structures and their potential control on depositional systems. The salt sheet is a plug-fed extrusion emplaced due to squeezing of a salt diapir under compression. The preserved mylonitic shear fabric in the evaporites indicates radial, south-directed emplacement of the salt sheet. Tectono-sedimentary relationships record the evolution of the salt structure, from initial diapiric growth, to salt sheet extrusion and posterior collapse. Syn-extrusion sediments record the variable bathymetry of the extruding salt sheet, with reefal carbonates building up on the crestal bulge while their deeper water equivalents accumulated on the extruding salt lobe. This is the first description of a salt allochthon still linked to its source diapir in the Eastern Alps.

Fluorescent-Tagged Antiscalants-The New Materials for Scale Inhibition Mechanism Studies, Antiscalant Traceability and Antiscaling Efficacy Optimization during CaCO3 and CaSO4·2H2O Scale Formation.

Equipment scaling leads to reduced production efficiency in a wide range of industrial applications worldwide. Various antiscaling agents are currently commonly used to mitigate this problem. However, irrespective of their long and successful application in water treatment technologies, little is known about the mechanisms of scale inhibition, particularly the localization of scale inhibitors on scale deposits. The lack of such knowledge is a limiting factor in the development of applications for antiscalants. Meanwhile, fluorescent fragments integrated into scale inhibitor molecules have provided a successful solution to the problem. The focus of this study is, therefore, on the synthesis and investigation of a novel fluorescent antiscalant: (2-(6-morpholino-1,3-dioxo-1H-benzo[de]isoquinolin-2(3H)yl)ethylazanediyl)bis(methylenephosphonic acid) (ADMP-F) which is an analog of the commercial antiscalant: aminotris(methylenephosphonic acid) (ATMP). ADMP-F has been found to effectively control the precipitation of CaCO3 and CaSO4 in solution and is a promising tracer for organophosphonate scale inhibitors. ADMP-F was compared with two other fluorescent antiscalants-polyacrylate (PAA-F1) and bisphosphonate (HEDP-F)-and was found to be highly effective: PAA-F1 > ADMP-F >> HEDP-F (CaCO3) and PAA-F1 > ADMP-F > HEDP-F (CaSO4·2H2O). The visualization of the antiscalants on the deposits provides unique information on their location and reveals differences in the "antiscalant-deposit" interactions for scale inhibitors of different natures. For these reasons, a number of important refinements to the mechanisms of scale inhibition are proposed.

Balancing the Strength-Impact Relationship and Other Key Properties in Polypropylene Copolymer-Natural CaSO4 (Anhydrite)-Filled Composites.

To develop novel mineral-filled composites and assess their enhanced properties (stiffness, a good balance between mechanical strength and impact resistance, greater temperature stability), a high-impact polypropylene copolymer (PPc) matrix containing an elastomeric discrete phase was melt mixed with natural CaSO4 ß-anhydrite II (AII) produced from gypsum rocks. First, in a prior investigation, the PPc composites filled with AII (without any modification) displayed enhanced stiffness, which is correlated with the relative content of the filler. The tensile and impact strengths dramatically decreased, especially at high filling (40 wt.%). Therefore, two key methods were considered to tune up their properties: (a) the ionomeric modification of PPc composites by reactive extrusion (REx) with zinc diacrylate (ZA), and (b) the melt mixing of PPc with AII surface modified with ethylenebis(stearamide) (EBS), which is a multifunctional processing/dispersant additive. The properties of composites produced with twin-screw extruders (TSEs) were deeply assessed in terms of morphology, mechanical, and thermal performance, including characterizations under dynamic mechanical solicitations at low and high temperatures. Two categories of products with distinct properties are obtained. The ionomeric modification by Rex (evaluated by FTIR) led to composites characterized by remarkable thermal stability, a higher temperature of crystallization, stronger interfacial interactions, and therefore noticeable mechanical properties (high tensile strength (i.e., 28 MPa), increased stiffness, moderate (3.3 kJ/m2) to good (5.0 kJ/m2) impact resistance) as well as advanced heat deflection temperature (HDT). On the other hand, the surface modification of AII with EBS facilitated the dispersion and debonding of microparticles, leading to composites revealing improved ductility (strain at break from 50% to 260%) and enhanced impact properties (4.3-5.3 kJ/m2), even at high filling. Characterized by notable mechanical and thermal performances, high whiteness, and a good processing ability, these new PPc-AII composites may be tailored to meet the requirements of end-use applications, ranging from packaging to automotive components.

Enhancing bauxite residue properties for plant growth: Gypsum and organic amendment effects on chemical properties of soil and leachate.

Here, we assess the effects of gypsum and local organic waste as amendments to non-weathered, filter-pressed bauxite residue (BR) to improve its properties and support plant growth. In addition, we monitored the leachate quality of the amended BR under progressive leaching that simulated precipitation conditions in Northern Brazil. Free-draining column tests consisting of BR amended with gypsum and organic waste, at 5% and 10% w/w, respectively, were leached for 8 weeks to assess the effects on the chemical composition of BR and the leachates. Adding gypsum to BR reduced the exchangeable sodium (Na) percentage (ESP) from approximately 79%-48%, whereas adding only organic waste had smaller effects on ESP (from ∼79% to âˆ¼ 70%). The mean leachate pH ranged from 8.7 to 9.4 for the gypsum, and organic waste amended BR, while this was 10.3 in the leachate of the unamended BR. The treatments had similar trends of electrical conductivity throughout the experiments and were below 2 dS/cm after 8 weeks, when ∼1.700 mm simulated precipitation had leached. Aluminium (Al), Arsenic (As), and Vanadium (V) concentrations in leachates of BR with gypsum, either alone or in combination with organic waste, were significantly lowered than in leachate of non-amended BR. By contrast, metal concentrations increased if organic waste was added to BR. We conclude that amending BR with gypsum, in combination with organic waste, significantly improves the chemical properties of the solid phase and achieved rehabilitation goals for SAR and EC of the leachates after 8 weeks of leaching. However, despite high leaching rates, rehabilitation goals for pH and ESP were not achieved with gypsum either alone or combined with organic waste.