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Purpose: To evaluate the in vitro accuracy of impressions obtained with two silicone and corresponding stone models using two laboratory scanners. Materials and Methods: A master model with synthe:c resin teeth with two single-unit crown prepara:ons was created and scanned using a 12-megapixel scanner. Five conven:onal impressions of the physical model were prepared with different silicone impression systems (Zhermack and Coltene) using the double-mix technique and poured with gypsum. The impressions and stone models obtained were scanned using two extraoral scanning systems (Iden:ca T500, Medit; S600 ARTI, Zirkonzahn). All best-fit superimposi:ons of the teeth areas were conducted between the master model and the scans of the impressions and models obtained with the two scanners. A P < .05 level was considered significant. Results: The Iden:ca T500 Medit scanner showed an accuracy of 102.34 (89.67, 115.01) µm for Coltene silicone and 79.51 (67.82, 91.21) µm for Zhermack silicone, while the S600 ARTI Zirkonzhan scanner presented 110.79 (98.24, 123.33) µm and 91.91 (81.29, 102.54) µm, respec:vely, with significant differences between scanners for Zhermack silicone (P = .008) and for the corresponding stone models (P = .002). Zhermack silicone presented overall discrepancies lower than Coltene silicone, with sta:s:cally significant differences in both scanners analyzed (P < .001; P = .017). However, the discrepancies found were within clinically acceptable values. With the Zirkonzahn scanner, discrepancies found in the Zhermack impressions were lower than in the corresponding stone models (P < .001). Conclusions: The direct digi:za:on of silicone impressions with laboratory scanners presented comparable results to conven:onal techniques with stone models. [ABSTRACT FROM AUTHOR]

Microorganisms inhabiting gypsum have been observed in environments that differ greatly in water availability. Gypsum colonized by microorganisms, including cyanobacteria, eukaryotic algae, and diverse heterotrophic communities, occurs in hot, arid or even hyperarid environments, in cold environments of the Antarctic and Arctic zones, and in saline and hypersaline lakes and ponds where gypsum precipitates. Fossilized microbial remnants preserved in gypsum were also reported. Gypsum protects the endolithic microbial communities against excessive insolation and ultraviolet radiation, while allowing photosynthetically active radiation to penetrate through the mineral substrate. We here review the worldwide occurrences of microbially colonized gypsum and the specific properties of gypsum related to its function as a substrate and habitat for microbial life on Earth and possibly beyond. Methods for detecting and characterizing endolithic communities and their biomarkers in gypsum are discussed, including microscopic, spectroscopic, chemical, and molecular biological techniques. The modes of adaptation of different microorganisms to life within gypsum crystals under different environmental conditions are described. Finally, we discuss gypsum deposits as possible targets for the search for microbial life or its remnants beyond Earth, especially on Mars, where sulfate-rich deposits occur, and propose strategies to detect them during space exploration missions. [ABSTRACT FROM AUTHOR]

To expand plaster utilization as a binder, mechanical behavior of sandwich panels consisting of two faces of plaster reinforced with fiberglass fabrics and a core of extruded polystyrene foam was studied. Using software based on the finite element method, computational models were utilized to simulate the four-point bending test. Two scenarios were examined: assuming a linear stress-strain curve for the material and employing nonlinear geometric analysis. These computational simulations allowed to determine loading limits and vertical displacements. After determining the flexural stiffness, the vibration response was calculated via an analytical procedure. This investigation proved that sandwich panels with greater thicknesses and volumes of reinforcements on the plaster faces exhibited greater load-bearing capacity, smaller displacements, greater resistance to traction and compression, and greater stiffness. Notably, panel 3, which had the thickness and volume content of reinforcement in the composite faces 24.71 and 66.67% higher, respectively, than reference panel, presented the best static and vibrational responses. [ABSTRACT FROM AUTHOR]

This article provides information on ettringite, a hydrated calcium sulfoaluminate mineral that belongs to the ettringite group. It describes the physical characteristics of ettringite, such as its hexagonal, prismatic crystals and color variations. The article also mentions the origins of the name ettringite and its cotype localities in the Ettringen district of Germany. Additionally, it discusses the village of Ettringen and its association with outdoor activities like rock climbing in basalt quarries. The article further explores the Bellerberg volcanic lava flows and their use in manufacturing querns and millstones. It highlights the Kalahari manganese field in South Africa as the primary natural locality for ettringite specimens, with larger crystals than any others known. The article focuses on the identification and properties of yellow ettringite found in the Kalahari manganese field, emphasizing the challenges in visually distinguishing it from other minerals in the area. It also delves into the role of ettringite in the deterioration of concrete and its stability under different conditions. The research for this article was funded by the National Research Foundation and CIMERA. [Extracted from the article]

Phosphogypsum (PG) is a solid waste generated by phosphate fertilizer industries that is currently used in concrete materials. However, adding PG to concrete usually results in reducing its water resistance and corrosion resistance. This paper presents a new method of applying PG to concrete to improve its water resistance. In this paper, a green superhydrophobic PG (SPG) coating was prepared using modified PG as a hydrophobic medium and cement as the bonding material. The contact angle between the superhydrophobic phosphogypsum coating (SPG coating) and water was 156°, and the coating reached a superhydrophobic state with good self-cleaning ability. Even when sandpaper was used to polish the coating, the water contact angle of the coating was still greater than 150°, indicating that the coating had good wear resistance. In addition, the results of water absorption and electrochemical experiments indicated that mortar coated with SPG had better water resistance and corrosion resistance than ordinary mortar. The SPG coatings with water resistance, wear resistance, and self-cleaning properties have potential applications in building exterior walls. [ABSTRACT FROM AUTHOR]

The accumulation of phosphogypsum (PG) has become a significant environmental and economic challenge, making PG reuse an urgent concern. This study aims to explore the potential of combining PG with steel slag (SS), ground granulated blast-furnace slag (GGBS), and cement clinker (CC) to create excessive-sulfate phosphogypsum slag cement (EPSC) for use in self-compacting concrete (SCC). However, residual acid and other impurities in PG can significantly slow down the setting time of EPSC. To optimize the setting time, different methods including wet grinding, washing, and the addition of pure gypsum, limestone powder (LP), and aluminum cement (AC) are used. Results show that the wet grinding method and washing method remove soluble phosphorus impurities and reduce fluorine ion levels by 64%. However, nonsoluble impurities that cannot be removed by wet grinding and washing continue to affect EPSC's setting time. Furthermore, the addition of LP shortens the setting time, but not enough. Using a 3% dosage of AC successfully reduces the setting time to a satisfactory level and EPSC SCC with a 28-day strength greater than 40 MPa is produced using the paste rheological threshold method. [ABSTRACT FROM AUTHOR]

In this article, a kind of original bamboo-fiber reinforced phosphogypsum composite wall was proposed. The axial compression tests of eight walls and finite element analysis were carried out. The failure modes and mechanical properties of the walls were explored, the influence of parameters on the axial compression performance of the walls was studied, and the calculation methods of the axial compression capacity and stiffness of the composite walls were proposed. The results show that the phosphogypsum cracked first in the composite walls during the loading process, the cracks gradually spreaded through and widened, and the bamboo tubes inside the composite walls were crushed. The buckling failure occurred in the pure original bamboo wall. The bearing capacity of the composite wall control specimen is 140% and 38.46% higher than that of the pure phosphogypsum wall and the pure original bamboo wall, respectively. The number of dovetail nails has no significant effect on the axial compression performance of the composite wall. The bearing capacity and stiffness of composite wall increase with the increase of bamboo number, wall thickness, bamboo wall thickness and phosphogypsum strength. The calculation method of axial bearing capacity and stiffness of composite wall based on bamboo content is proposed. The finite element simulation results are in good agreement with the experimental and theoretical calculation results. The theoretical calculation method has high accuracy. The composite wall realizes the complementary advantages of original bamboo and phosphogypsum, which provides reference for the development and application of green buildings. [ABSTRACT FROM AUTHOR]

The selective flotation separation of gypsum and quartz in phosphogypsum (PG) is an urgent problem that is very important for the high‐value utilization of PG. In the work, dodecyl amine hydrochloride (DH) was introduced as a collector for the selective flotation separation of gypsum and quartz. The flotation property and selective mechanism of DH on the surface of gypsum and quartz were researched by single mineral flotation experiments, Fourier transform attenuated total reflection infrared spectroscopy analyzer, zeta potential analyzer, X‐ray photoelectron spectrum, molecular dynamic (MD) simulation, etc. Additionally, H+ was introduced into the mineral‐water system simulated by MD to take into account the effect of acidic conditions on the adsorption of DH. The pre‐adsorption of H+ on the quartz surface under strongly acidic conditions hindered the electrostatic force adsorption of DH on the quartz surface. Furthermore, DH was adopted as a collector in the direct flotation recovery of gypsum from PG, and the gypsum concentrates with productivity of 69.85%, CaSO4·2H2O content of 96.33%, and whiteness of 55.00% were obtained. The SiO2 content in the gypsum concentrate decreased from 9.08% to 0.616%. It suggested that DH could serve as a promising collector in the selective separation of gypsum and quartz in PG via flotation. [ABSTRACT FROM AUTHOR]

In order to study the effects of pre‐crack inclination angle and filling material on granite, uniaxial compression tests were performed on pre‐cracked granite specimens without filling material and specimens filled with epoxy resin, gypsum, and organosilicon. Results indicate that the peak strength and apparent stiffness of pre‐cracked granite without filling materials increase with increasing pre‐crack inclination angle. The strain energy absorbed by the filling material improves the energy storage limit, inhibits the energy release effect when microcracks are connected to each other, and ultimately improves the compressive resistance and energy storage capacity. The strengthening effect of gypsum and epoxy resin is relatively better, which is more significant when the pre‐crack inclination angle equals 0°–60°. Finally, a damage constitutive model is established, which is in good agreement with the test and numerical simulation data. The results can provide reference for the research of grouting reinforcement of rock masses. Highlights: The effects of pre‐crack inclination angle and filling material are analyzed.The evolution law of energy mechanism is analyzed.The damage constitutive (DC) model of cracked rocks is proposed.The strengthening mechanism of energy storage effect of filled cracks was discussed. [ABSTRACT FROM AUTHOR]

In vitro biomineralization, carried out under laboratory conditions, provides scope for highly controlled crystallization events, at different stages of the formation reaction. This crystallization control is exerted using foreign substances or additives, which are usually organic compounds. Here, we have shown how with the use of homeopathic medicine Symphytum Q, the morphology of calcium carbonate is changed from its rhombohedral, the most stable morphology to spherical morphology, while the phase remains the same. A study has also been done on the formation of gypsum with varying parameters. [ABSTRACT FROM AUTHOR]

Copyright of Nonferrous Metals (Extractive Metallurgy) is the property of Beijing Research Institute of Mining & Metallurgy Technology Group and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Romanian Journal of Civil Engineering / Revista Română de Inginerie Civilă is the property of Matrix Rom and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Limestone substrates cover 20–30% of the continents and are the habitat of many calcareous fern species, which grow preferably or exclusively on this substrate. In this review, we resume the limestone properties and their implications for calcareous ferns. Additionally, we investigate the taxonomic distribution of limestone ferns by comparing five limestone regions and six mainly lithophytic genera to understand what proportion of ferns and which genera primarily colonise limestone in each region. Mexico is presented as a more detailed case study. Calcareous ferns have to deal with higher soil alkalinity, increased levels of Ca, Mg, and carbonates, lower P, Fe, and Zn availability, and often shallow, dry soils. Limestone ferns comprised 8-13% of the regional floras (except for South Africa) and were most diverse in Pteridaceae, Aspeniaceae, and Dryopteridaceae. However, the relative proportion of calcareous ferns in each of the six genera varied from region to region. The highest proportions of limestone species were detected in Ctenitis (73% in Jamaica), Adiantum and Asplenium (50% in Thailand), Anemia (40% in Jamaica), and Polystichum (35% in Jamaica and 33% in China). These results indicate a regionally independent evolution of limestone specialisation in ferns. Gypsum and serpentine ferns have to cope with even more extreme substrate conditions, are even rarer and may have evolved from limestone ferns. [ABSTRACT FROM AUTHOR]

The utilization of industrial solid waste in mines is an important approach to resource utilization. The backfill material in mines is mainly composed of solid waste, which plays a supporting role. The excitation effect of lime on phosphogypsum and fly ash in backfill was studied in this paper. The macroscopic and microscopic characteristics of the backfill material were tested using uniaxial compression, nuclear magnetic resonance, scanning electron microscopy, and electrochemical techniques, and a relationship model was established between them. Furthermore, the influence of industrial solid waste on the properties of the backfill material under the action of lime and the hydration mechanism between different industrial solid wastes were studied. The results show that (1) under the action of lime, fly ash reacts with lime to produce C-S-H and C-A-H, and then C-A-H reacts with phosphogypsum to produce AFt. (2) The excess phosphogypsum also fills the pores. Therefore, 1.8% lime reduces the porosity of the backfill by 17.88% and increases the strength by 21.57%. (3) The cross-scale relationship shows that strength is inversely proportional to each type of pore content and fractal dimension, and it logarithmically increases with impedance at different frequencies. The lower the frequency, the stronger the relationship is. (4) This study indicates that industrial solid waste is a suitable cement replacement. [ABSTRACT FROM AUTHOR]

In recent decades, plastic waste management has become one of the main environmental challenges for today's society. The excessive consumption of so-called single-use plastics causes continuous damage to ecosystems, and it is necessary to find alternatives to recycle these products. In this work, a mechanical and hygrothermal characterisation of novel plaster composites incorporating LDPE waste in their interior was carried out. Thus, prefabricated plasterboards have been designed with a partial replacement of the original raw material with recycled LDPE in percentages of 5–10–15% by volume. The results show how these new composites exceeded the 0.18 kN minimum breaking load in panels in all cases, while decreases in density and thermal conductivity of up to 15% and 21%, respectively, were obtained. In addition, an increase of 3.8%in thermal resistance was obtained by incorporating these new gypsum boards in lightweight façade walls through simulations. In this way, a new pathway was explored for the recovery of these wastes and their subsequent application in the construction sector. [ABSTRACT FROM AUTHOR]

Phosphogypsum is a solid waste with great environmental stockpile pressure produced by the wet production of phosphoric acid. Although there are various methods to purify and utilize phosphogypsum, the means for environmentally friendly, low energy consumption, and high value-added utilization still need to be further explored. Here, CaSO4·2H2O crystal was directly purified and regulated from phosphogypsum by using the anti-solvent method. The antisolvent can be adsorbed in the c-axis direction of the crystal and further inhibit the growth rate in this direction, resulting in a change in the morphology of the crystal. By adjusting the polarity and chain length of the anti-solvent, the morphology of CaSO4·2H2O crystal can change from butterfly-like flake crystals to hexagonal prism-like crystals. When n-propanol with long chain was used as the anti-solvent, the morphology of the CaSO4·2H2O crystal showed a hexagonal prism with a specific surface area of 19.98 m2/g and a Cu2+ loading efficiency of 52.67%. The encouraging results open up new possibilities for the application of phosphogypsum. [ABSTRACT FROM AUTHOR]

This study investigates, in the first part, the synthesis and purification of a poorly crystalline hydroxyapatite (HAp) using natural Moroccan phosphate (Boucraa region) as a raw material. Despite its successful preparation, the obtained HAp was contaminated by several metallic cations (mostly Cd, Pb, Sn, Ti, Mn, Mg, Fe, and Al) migrated from the natural rocks during the digestion process, inhibiting HAp application in several sectors. To minimize the existence of these elements, the dissolution–precipitation technique (DP) was investigated as a non-selective purification process. Following the initial DP cycle conducted on the precipitated HAp, the removal efficiency was approximately 60% for Al, Fe, Mg, Mn, and Ti and 90% for Cd and Pb. After three consecutive DP cycles, notable improvement in the removal efficiency was observed, reaching 66% for Fe, 69% for Mg, 73% for Mn, and 74% for Al, while Cd, Pb, and Ti were totally removed. In the second part of this study, the purified HAp was digested using sulfuric acid to produce high-quality phosphoric acid (PA) and gypsum (GP). The elemental analysis of the PA indicates a removal efficiency of approximately 89% for Fe and over 94% for all the examined cations. In addition, the generated GP was dominated by SO3 and CaO accompanied with minor impurities. Overall, this simple process proves to be practically useful, to reduce a broad spectrum of cationic impurities, and to be flexible to prepare valuable products such hydroxyapatite, phosphoric acid, and gypsum. [ABSTRACT FROM AUTHOR]

The use of green methods to treat industrial waste and waste reuse has become a key environmental issue. In order to achieve this goal, this study treated waste phosphogypsum (PG) and produced modified PG biochar to adsorb and remove phosphorus from PG leachate, so that the PG pollution problem was controlled. In this study, PG was modified with sodium carbonate (Na2CO3) to prepare a modified PG biochar that was used for the removal of phosphorus-containing wastewater. An X-ray diffraction (XRD) analysis of the modified PG revealed that the main component was calcium carbonate (CaCO3), and a suitable amount of modified PG could load calcium oxide (CaO) onto the biochar and improve its physical properties. The experimental results showed that the modified PG biochar had a maximum phosphorus adsorption capacity of 132 mg/g. A further investigation of the mechanism of adsorption revealed the importance of electrostatic attraction and chemical precipitation, and it was found that the CaO in the modified PG biochar could effectively facilitate the conversion of phosphate to hydroxylapatite (Ca5(PO4)3OH) in water. The phosphorus removal rate from leachate obtained from a landfill containing PG was 99.38% for a specific dose of the modified PG biochar. In this study, a PG pollution control technology was developed to realize the goal of replacing waste with waste. [ABSTRACT FROM AUTHOR]

Gypsum ecosystems occur in arid and semi-arid areas, where evaporation is intense and annual precipitation is low and insufficient to leach the gypsum. They host sparse and scattered vegetation, composed of species specialized in this soil type. In Cyprus, gypsophilous vegetation is part of the priority habitat *1520 Iberian gypsum steppes (Gypsophiletalia) characterized by Campanula fastigiata, Gypsophila linearifolia, and Teucrium salaminium. Despite the ecological importance of gypsophilous vegetation, its distribution and ecology in Cyprus is still understudied. This study aimed to provide the first comprehensive account of the gypsum communities, focusing on the distribution of gypsophytes in relation to the substrate and the floristic composition of gypsum soils. Floristic inventory was carried out in 27 sites with gypsum soil. Biophysical information and data about human impact were also recorded. A total of 97 taxa were identified, including three gyspophile species, two gypsoclines, 20 gypsovags, and 72 waifs. A new endemic Rostraria hadjikyriakou was recorded in five locations. The known geographical distribution of gypsophilous vegetation has been updated. For 35% of the sites, gypsophilous vegetation was recorded for the first time while none of the characteristic gypsophilous species was found in the western part of the island. [ABSTRACT FROM AUTHOR]

The Pulang giant porphyry Cu-Mo polymetallic deposit is located in the Zhongdian area in the center of the Sanjiang Tethys tectonic domain, which was formed by the westward subduction of the Garze-Litang oceanic slab beneath the Zhongza massif. Chalcopyrite-pyrrhotite-pyrite-molybdenite occurs as disseminations, veins, veinlets, and stockworks distributed in the K-silicate alteration zone in the monzonite porphyry, which is superimposed by propylitization. The chemical compositions of biotite and amphibole analyzed by electron probe microanalysis (EPMA) indicate that the ore-forming magma and exsolved fluids experienced a continuous decrease in the oxygen fugacity (fO2). Primary amphibolite and biotite (type I) crystallized at relatively high temperatures (744–827 °C) and low fO2 (logfO2 = − 12.26 to − 11.91) during the magmatic stage. Hydrothermal fluids exsolved from the magma have a relatively lower temperature (621–711 °C) and fO2 (logfO2 = − 14.36 to − 13.32) than the original magma. In addition, the presence of a high abundance of pyrrhotite and an insufficiency of primary magnetite and sulfate in the ore (i.e., anhydrite and gypsum) indicate that the deposit may be a reduced porphyry deposit. Magma and fluid fO2 results, combined with previous research on magmatic fO2 at the Pulang deposit, indicate that the magma associated with the reduced Pulang ore assemblages was initially generated as a highly oxidized magma that was subsequently reduced by sedimentary rocks of the Tumugou Formation. [ABSTRACT FROM AUTHOR]

The coexistence of different foulant compositions in the feed water of reverse osmosis (RO) systems causes serious complications in the fouling process of the membranes. Hence, in this technical research, the phenomenon of combined inorganic (gypsum)-colloidal (silica particles) fouling (inorganic-colloidal fouling) of brackish water RO (BWRO) process was studied in the lab-scale experiments. Moreover, the effect of the presence of air micro–nano bubbles (AMNBs) in the feed water; as a new practical method for control of membrane fouling, was investigated on this phenomenon. For this purpose, a suspension with the potential of inorganic scaling [calcium sulfate, Saturation index (SI)=0.96 ] and colloidal fouling (colloidal silica, 50 mg/L) was used to form the inorganic and colloidal foulings (simultaneously) on the membrane surface during the inorganic-colloidal fouling process. All experiments were performed twice, once in the absence and once in the presence of AMNBs. Finally, the results of this research were compared with the results of the inorganic and colloidal fouling studies. Based on the results, the inorganic-colloidal fouling formed a dense and compact fouling layer on the membrane surface, which severely reduced the permeate flux (76.3%) and salt rejection (4%). The amount of decrease of these two parameters in inorganic-colloidal fouling was much higher than each of individual inorganic and colloidal foulings. In the presence of AMNBs, both types of inorganic and colloidal foulings greatly reduced and the major portion of inorganic-colloidal fouling was related to the colloidal fouling. Thus, a significant decline was observed in adverse effects of inorganic-colloidal fouling on the membrane performance and the permeate flux and salt rejection decreased by 18.5% and about 1%, respectively. The results of this study could introduce the micro–nano bubbles (MNBs) technology as an effective method to inhibit the inorganic-colloidal fouling in RO systems. Practical Applications: Today, reverse osmosis processes are known as efficient technologies for supplying drinking water from brackish and sea water resources due to their high ability to remove various compounds. The separated compounds from the water accumulate near the membrane surface and consequently deposit on it and/or inside its pores. This phenomenon is called membrane fouling and has adverse effects on the performance of reverse osmosis processes. Water resources usually have different types of pollutants that simultaneous presence of them can intensify the membrane fouling process. Gypsum scaling and colloidal silica fouling are two major common types of reverse osmosis membrane fouling. Therefore, in this research, the effects of the inorganic-colloidal fouling were studied on the performance of a commercial brackish water reverse osmosis membrane, in presence and absence of air micro–nano bubbles. The results showed that the combined fouling formed a complex fouling layer on the membrane surface in absence of air micro–nano bubbles. In real-scale reverse osmosis process, this layer can severely reduce the membrane permeate flux and salt rejection which result to increase in the operational and maintenance costs. Alternatively, the presence of air micro–nano bubbles in the reverse osmosis feed flow could limit both inorganic and colloidal foulings and their synergetic effects on each other. [ABSTRACT FROM AUTHOR]

To reduce environmental pollution and conserve natural resources, calcined oyster shell ash (COSA), class F fly ash (FFA) and flue gas desulfurisation gypsum (FGDG) were used in an attempt to improve the engineering properties of alkali-activated ternary cementitious paste. The COSA – obtained by calcining crushed oyster shells at 800°C for 3 h and then grinding to pass through a no. 100 sieve – was used to substitute FFA at rates of 2.5, 5.0 and 7.5 mass%. The alkali solution used was 10M sodium hydroxide and sodium silicate with a modulus of 2.5. The hardened paste with 7.5% COSA, 1% FGDG and ratio of weight of added water to dry binder of 0.09 at 56 days had the highest compressive strength of 62 MPa. Microstructural analyses (scanning electron microscopy and energy-dispersive X-ray spectroscopy) showed that the resulting calcium aluminosilicate hydrate gel was found to have a compact microstructure, which improved the compressive strength of specimens. In summary, COSA successfully replaced natural limestone as a calcium oxide activator to manufacture an alkali-activated ternary cementitious paste containing FFA and FGDG. [ABSTRACT FROM AUTHOR]

Nitrification is the core step of the soil nitrogen cycle and directly affects the nitrogen use efficiency in agricultural systems. Biochar and gypsum are two important soil amendments widely used in coastal saline farmland. However, little is known about their effects on nitrification and ammonia-oxidizing microorganisms. A one-year pot experiment with three treatments including biochar application (BC), gypsum application (SG), and no amendment (CK) was conducted, and the responses of the nitrification rate, amoA gene copies, and the diversity and community structure of ammonia-oxidizing archaea (AOA) and bacteria (AOB) to biochar and gypsum were evaluated. The results indicated that biochar and gypsum application both resulted in alterations to the soil properties. They both had inhibiting effects on nitrification and AOB amoA gene copies, whereas they had no significant effect on AOA amoA gene copies. Biochar had no significant effect on the diversity indexes of AOA, but it significantly reduced the Shannon index of AOB. Meanwhile, gypsum had no significant influence on the diversity indexes of both AOA and AOB. Biochar and gypsum did not significantly affect the community structure of AOA but did induce changes in that of AOB. In detail, biochar significantly enhanced the relative abundance of the dominant cluster Nitrosospira, whereas gypsum led to a notable increase in the relative abundance of unclassified_o_Nitrosomonadales. The Shannon index of AOB had a significant negative correlation with soil TOC, TN, and NH4+ content, and soil pH was the first primary environmental factor that affected the AOB community structure. In conclusion, biochar and gypsum inhibited nitrification by suppressing the activities of AOB and changed the diversities and community structure of AOB by altering related soil properties. [ABSTRACT FROM AUTHOR]

Creep is a distinctive mechanical response observed in soft rocks like salt. Typically, there are three primary methods which have been widely applied in the investigation of salt creep within high-purity and thick formations: analytical solutions, triaxial experiments, and numerical simulations. However, for ultra-deep composite salt layers in the Tarim Basin, Xinjiang Uygur Autonomous Region, China, the intense tectonic movement has resulted in salt formations that exhibit distinct characteristics from conventional fine-grained rock salt. In addition, the presence of interlayers of clay minerals within the salt makes the creep behavior even more complex. The ultra-deep composite rock salt exhibits incompatible deformation phenomena which cannot be explained by continuum theory. In addition, the proportion of different components in the standardized sample is usually uncertain and that, doubtlessly, introduces an uncontrollable variable into the creep experiments. In simulation, the morphology of the interfaces is usually not considered. Sometimes they are treated as separate layers, leading to significant disparities between physical model and reality. Therefore, all these approaches have limitations. This paperwork introduces a comprehensive and novel approach for investigating rock salt creep behavior. Based on image identification, the contours of interface from real salt samples are first extracted and imported into finite element method (FEM) program for simulations. Verified by digital image correlation (DIC) experiments, it reveals that under uniaxial stress state, near the front edge of gypsum, the compression of composite salt rocks increases as creep progresses. Tensile strain tends to appear in the segments with angles greater than 45°, causing fissures of 0.01 µm width within NaCl. From electron microscopy, localized damage was observed, revealing micro-cracks of 1–2 µm width occurring predominantly at interfaces, where shear strain accumulates, especially in the junction area. In addition, shear strain tends to accumulate near segments with angles ranging from 0° to 35°. Through precise interface morphology description, the results of simulation could be much more practical and reliable. The methodology in this study can actually be adopted in the simulation of any types of rock. Highlights This paperwork introduces a comprehensive and novel approach for investigating rock salt creep behavior especially the composite. Through precise interface morphology description, the results of simulation could be much more practical and reliable. This eliminates the need to treat the interfaces as separate layers when performing multilayer simulations. Shear strain predominantly accumulates on either side of interfaces which is caused by incompatible deformation of different components. The result of simulation is proved by the experiments and they fit well especially near the surface。 Furthermore, combining this method with CT scan results provides an effective means to create a three-dimensional model of the sample. [ABSTRACT FROM AUTHOR]

Sulfate plays a critical role in portland cement. The internal gypsum (CaSO4·2H2O) incorporating with clinker controls the hydration of cement, while the external gypsum can attack the hydration products. Magnesium sulfate is renowned for sulfate attack on concrete. This study aims to investigate the impact of the internal Mg2+ addition on the composition and microstructure of hardened portland cement paste. Notably, the test results demonstrate that internal Mg2+ does not show the same aggressive effect as external Mg2+ on the destabilization of portland cement. Instead, internal Mg2+ infiltrates into the calcium-silicate-hydrate (C-S-H) gels, displacing the Al-O tetrahedra on the Si chain, forming C-(A, M)-S-H gels by converting Ca octahedra to Mg octahedra or Al-O tetrahedra to Mg-O tetrahedra. This process contributes to a decrease in the Al/Si ratio and mean chain length of the C-S-H gels. Additionally, the displaced Al-O tetrahedra from the C-S-H gels react with AFt, resulting in the AFm formation. Consequently, these structural changes in the C-S-H gels, along with additional pore filling through AFm precipitation, play a significant role in refining the pore structure. [ABSTRACT FROM AUTHOR]

Soil salinisation poses a significant threat to global agricultural production and food security. China is among the countries most severely impacted by soil salinisation. To investigate the improvement technology for saline–alkali stress in buckwheat, a typical multigrain crop in northwest China, a coupling regulation study using desulfurisation gypsum and polyacrylamide (PAM) was conducted in 2019 and 2020. Desulfurisation gypsum was applied at 0, 5.5, 11, 16.5 and 22 kg·ha−1, while PAM was applied at 0, 15, 30, 45 and 60 kg·ha−1. The results demonstrated that applying 11 t·ha−1 desulfurisation gypsum and 30 kg·ha−1 PAM effectively reduces soil salinity and pH, averaging 81.79% and 6.07%, respectively. Furthermore, it did not cause soil heavy metal pollution and created the best soil environment for buckwheat growth. Among the models tested, the nonrectangular hyperbolic model was the most accurate in describing buckwheat's photosynthetic light response. The optimal treatment for achieving the best photosynthetic performance—measured by apparent quantum efficiency, maximum net photosynthetic rate, light compensation point, light saturation point, dark respiration rate, stomatal conductance, intercellular CO2 concentration, transpiration rate, leaf water use efficiency and yield—was achieved through applying 11 t·ha−1 desulfurisation gypsum and 30 kg·ha−1 PAM. Therefore, desulfurised gypsum and PAM should be applied at 11 t·ha−1 and 30 kg·ha−1, respectively, to improve buckwheat's adaptability to different light intensities while promoting its photosynthetic response in saline–alkali soils. This study provides an effective technical scheme for reducing salt and promoting the growth of crops under salinity stress, which is of great significance for improving salinity land in arid areas. [ABSTRACT FROM AUTHOR]

The geochemical cycle of strontium is intimately linked to the long-term cycle of carbon, for instance, through their mutual involvement in continental weathering and marine carbonate sedimentation. Stable strontium isotopes (δ 88/86Sr) have recently emerged as a valuable tool, complementing radiogenic Sr isotope ratios (87Sr/86Sr), to further our understanding of the Sr cycle. Stable strontium isotopes are sensitive to both the sources of strontium (e.g., silicate versus carbonate weathering) and to earth surface processes (e.g., mineral precipitation from solution). Gypsum, a common evaporitic mineral, precipitates directly from seawater and holds the potential to serve as a marine archive for studying the elemental cycle of Sr. In addition, the impact of gypsum formation on the marine strontium isotope budget has been a matter of speculation due to the limited information on the isotope fractionation of Sr in gypsum. Here, we explore the behavior of strontium isotopes during gypsum precipitation and provide the first-order estimates of the associated isotope fractionation. Gypsum was produced through the evaporation of natural seawater in a series of experiments. Strikingly, in contrast to the fractionation of Ca isotopes into gypsum, as well as Sr isotopes into carbonate minerals, heavier isotopes of Sr are preferentially incorporated into gypsum with an estimated average isotope fractionation of ∼0.20‰ (range between 0.14–0.27‰). The variability in the observed experimental isotope fractionation is suggested to be the result of admixture of aragonite in the precipitate, surface-specific rate-controlled effects, and/or mineral occlusion (i.e., capturing of unfractionated Sr). Despite these complications, gypsum has the potential to effectively resolve significant variations in past seawater δ 88/86Sr following the suggested approach, which involves careful sample selection based on radiogenic Sr data, avoidance of aragonite admixtures, and ensuring a large dataset of coeval samples. Mass balance considerations indicate that the formation of giant evaporite deposits has the potential to induce only minimal, short-term, alterations in seawater δ 88/86Sr, largely not discernible due to the uncertainties in the existing Sr isotope records. Finally, we find that weathering of 88Sr-enriched marine gypsum exposed on the continents is likely a significant source of Sr to the ocean. This Sr source can explain at least 25% of the apparent mismatch between the observed global riverine δ 88/86Sr and that estimated from the weathering of carbonate and silicate lithologies only. [ABSTRACT FROM AUTHOR]

Gypsum is a common mineral at Gale crater on Mars, currently being explored by the Mars Science Laboratory (MSL) rover, Curiosity. In this paper, we summarize the associations of gypsum with other sulfate minerals (bassanite, anhydrite, jarosite, starkeyite, and kieserite) from the lowest levels of the crater's northern moat zone (Aeolis Palus) up through ~0.8 km of the stratigraphic section in the lower slopes of the sedimentary mound developed around the central peak, Aeolis Mons (informally, Mount Sharp). The analysis is based on results from the CheMin X-ray diffraction instrument on Curiosity, supplemented with information from the rover's versatile instrument suite. Gypsum does not occur with the same frequency as less hydrous Ca-sulfates, likely, in most cases, because of its dehydration to bassanite and possibly to anhydrite. All three of these Ca-sulfate phases often occur together and, along with other sulfates, in mixed assemblages that are evidence of limited equilibration on a cold, dry planet. In almost all samples, at least one of the Ca-sulfate minerals is present, except for a very limited interval where jarosite is the major sulfate mineral, with the implication of more acidic groundwater at a much later time in Gale crater's history. Although observations from orbit reveal a sulfate-rich surface, currently active dark basaltic dunes at Gale crater have only small amounts of a single sulfate mineral, anhydrite. Gale crater has provided the most complete mineralogical analysis of a site on Mars so far, but the data in hand show that Gale crater mineralogy is not a blueprint with planet-wide application. The concurrent study of Jezero crater by the Mars 2020 mission and comparisons to what is believed to be the most extensive deposit of gypsum on Mars, in the dune fields at the north polar ice cap, show significant diversity. Unraveling the stories of gypsum and other sulfates on Mars is just beginning. [ABSTRACT FROM AUTHOR]

A novel synthesis process and characterization of nano-calcium fluoride (n-CaF2) single crystal prepared from phosphogypsum waste. The phosphogypsum (CaSO4·2H2O) powder has been mechanically mixed with NH4F in presence of a controlled amount of water. The mixture still sintered for 48 hours until the formation of nano calcium fluoride particles. The n-CaF2 particles have been characterized by several techniques, The techniques utilized included X-ray diffraction (XRD), infrared spectroscopy (IR), and scanning electron microscopy (SEM). Therefore, it was confirmed that very pure n-CaF2 was obtained with a Ca/F ratio of 0.5 and an average crystalizing size measured according to the Debye-Scherrer equation of 11 nm. Based on the findings reached, The characterization data revealed successful synthesis of n-CaF2 from phosphogypsum. Additionally, the adsorption performance of the elaborated n-CaF2 was tested in Reactive Blue 21 (RB21) anionic dye removal, Adsorption tests were conducted in a batch reactor, focusing on key factors such as contact time, which can significantly influence the adsorption results. adsorption amount, pH, and dye concentration were tested. Hence results show an important adsorption performance of n-CaF2 with Reactive Blue 21 removal rate up to 90%. [ABSTRACT FROM AUTHOR]

Abstract—The possibility of synthesizing inorganic thermofoam silicate vitrified materials from technogenic and natural raw materials has been studied and substantiated. Compositions and modes for obtaining quality products have been selected. On the basis of microsilica and nepheline concentrate with the addition of chalk and gypsum, thermofoam silicates with a density of 0.49–0.52 g/cm3, a strength of 2.7–3.10 MPa, a reduced thermal conductivity of 0.059–0.062 W/(m K), and a water absorption of 12–18% have been synthesized. [ABSTRACT FROM AUTHOR]

The utilization of waste generated from industrial production is a burden to overcome for society to reach a circular economy. Usually, production waste is associated with low-quality materials compared to its natural counterparts. In some cases, high-purity materials are generated, while different hazardous substances such as heavy metals, radioactive elements, or organic chemical substances are pollutants that often limit the materials' further application. One such material that has accumulated for decades is phosphogypsum (PG). The extraction of fertilizers from metamorphous rocks results in large quantities of PG. Until now, PG has been deposited in large stockpiles near the production plant, causing problems for the environment in the surrounding area. However, the chemical composition of PG places it as a high-purity artificial gypsum material, which means that it could be used as a substitution or supplementary material in gypsum-based material production. The concerns, with respect to both legislation and prevailing prejudices in society, about its impurities strongly limit its application. This manuscript reviews current research practices for the effective use of PG and analyzes the importance of the circular economy. A life cycle assessment of current state-of-the-art technologies regarding PG application is proposed. [ABSTRACT FROM AUTHOR]

To investigate the macroscopic mechanical properties and failure evolution mechanism of desulfurization gypsum–fly ash fluid lightweight soil, a microscale numerical model using PFC2D (Particle Flow Code) was constructed. Uniaxial compression tests were conducted to determine the microscopic parameters of the model, extracting information on the discrete fracture network type, quantity, age, and particle displacement trend. The crack morphology and propagation evolution of desulfurization gypsum–fly ash fluid lightweight soil were explored, and the destructive properties of desulfurization gypsum–fly ash fluid lightweight soil material were evaluated through energy indicators. The research findings suggest that the discrete element numerical model effectively simulates the stress–strain curve and failure characteristics of materials. Under uniaxial compression conditions, microcracks dominated by shear failure occur in the initial loading stage of desulfurization gypsum–fly ash fluid lightweight soil, with a through crack dominated by tensile failure appearing once the load exceeds the peak stress. The dissipated energy evolution in the flow state of desulfurization gypsum–fly ash fluid lightweight soil is relatively gentle, leading to delayed cracking after surpassing the peak stress point. [ABSTRACT FROM AUTHOR]

Abstract\nHIGHLIGHTSElectrolytic manganese slag (EMR) is a solid waste generated in the manganese hydrometallurgy process. It not only takes up significant land space but also contains Mn2+, which can lead to environmental contamination. There is a need for research on the treatment and utilization of EMR. Improved EMR substrate for Pennisetum sinese Roxb growth was determined in pot planting experiments. The study tested the effects of leaching solution, microorganisms, leaf cell structures, and growth data. Results indicated a substrate of 45% EMR, 40% phosphogypsum, 5% Hericium erinaceus fungi residue, 5% quicklime, and 5% dolomite sand significantly increased the available phosphorus content (135.54 ± 2.88 μg·g−1) by 17.95 times, compared to pure soil, and enhanced the relative abundance of dominant bacteria. After 240 days, the plant height (147.00 ± 0.52 cm), number of tillers (6), and aerial dry weight (144.00 ± 15.99g) of Pennisetum sinese Roxb increased by 5.81%, 200%, and 32.58%, respectively. Analyses of leaves and leaching solution revealed that the highest leaf Mn content (46.84 ± 2.91 μg·g−1) being 3.38 times higher than in pure soil, and the leaching solution Mn content (0.66 ± 0.13 μg·g−1) was lowest. Our study suggested P. sinese Roxb grown in an improved EMR substrate could be a feasible option for solidification treatment and resource utilization of EMR.The waste solid resource utilization was achieved.The growth and ecological restoration value of Pennisetum sinese Roxb in an improved EMR substrate was found.An optimal ratio of improved EMR substrate was proposed.The waste solid resource utilization was achieved.The growth and ecological restoration value of Pennisetum sinese Roxb in an improved EMR substrate was found.An optimal ratio of improved EMR substrate was proposed. [ABSTRACT FROM AUTHOR]

Understanding the geometric dimensions of pipes formed during backward erosion piping (BEP) is crucial for comprehending the BEP mechanism and conducting numerical simulations. However, current research primarily focuses on the two-dimensional morphology of pipes, with a lack of sufficient understanding regarding their three-dimensional (3D) characteristics. To study the 3D geometric characteristics of the pipe, the 3D size of the pipe was measured and analyzed using the gypsum injection method and 3D laser scanning method in this study. The variations in pipe depth, width, and the ratio of width to depth were investigated in detail. And the influence of cover plate roughness and sand compactness on the 3D geometry of the pipe was clarified. It is found that the cross-section shape of the pipe is approximately rectangular, with the horizontal scale being significantly larger than the vertical scale. With increasing distance from the outlet hole, there is a gradual decrease in both the depth and width of the pipe. The relationship between the pipe's depth and width with respect to its length can be described using linear functions. As the compactness of sand layer increased, the depth and width of the pipe decreased to a certain extent. [ABSTRACT FROM AUTHOR]

In the present study, the chemical composition, mineralogy, and mechanisms of alteration of a cementitious grout based on a CEM III/C with addition of smectite, hydrotalcite, and silica fume, are studied using a combination of chemical and physical methods. This material was designed in the context of geological repository of radioactive wastes, with a twofold aim: first, to fill the technical voids left by drilling operations at the interface between the geological formation and the disposal galleries. Second, to neutralize a potential acidic transient due to pyrite oxidation, and to create an environment that favors low corrosion rates of carbon steels. The grout is mainly composed of calcium silicate hydrates having a Ca/Si ratio of ~0.8, incorporating Al in the bridging site of the Si chains (C-A-S-H), and accounting for 29–36 wt.% of the sample. It also contains silica fume (38–48 wt.%), smectite with interlayer Na (11–17 wt.%), hydrotalcite with interlayer CO32− (3–4 wt.%), and lower amounts of portlandite, calcite, and possibly gibbsite and gypsum. Upon alteration by water in a flow-through reactor, the main modifications affecting the sample are calcite and gypsum dissolution, hence releasing aqueous Ca2+ that is adsorbed in smectite interlayer by replacing Na+, and stoichiometric C-A-S-H dissolution. The evolution of solution chemistry and of the solid phase composition are reproduced successfully using a thermokinetic model. [ABSTRACT FROM AUTHOR]

As the main hydration product of magnesium oxysulfate (MOS) cement, 517 phase (5Mg(OH)2·MgSO4·7H2O) is one of the main sources of MOS cement strength. This paper mainly explores the erosion process and mechanism of calcium ions in the 517 phase. The 517 phase with 94.56% purity was synthesised and the erosion effect of different calcium salts on the 517 phase was characterised. Results show that, in the solution, Ca2+ combined with SO42− in the 517 phase, resulting in an increase in the spacing between the MgO6 octahedron layers in the 517 phase, thus destroying the structure of the 517 phase. Moreover, when ions diffused, the MgO6 octahedron and Cl− recombined into the 518 phase (5Mg(OH)2·MgCl2·8H2O). In addition, insoluble weddellite was found to erode the 517 phase to a certain extent, whereas the 517 phase blended with gypsum was stable. The simulation results of molecular dynamics also showed that Ca2+ had better adsorption ability for SO42− and Cl− than Mg2+. When it was in contact with the 517 phase, Ca2+ was absorbed near SO42− and Cl− was brought into the system. [ABSTRACT FROM AUTHOR]

This review comprehensively explores fluoride removal from phosphogypsum, focusing on its composition, fluorine-containing compounds, characterization methods, and defluorination techniques. It initially outlines the elemental composition of phosphogypsum prevalent in major production regions and infers the presence of fluorine compounds based on these constituents. The study highlights X-ray photoelectron spectroscopy (XPS) as a pivotal method for characterizing fluorine compounds, emphasizing its capability to determine precise binding energies essential for identifying various fluorine species. Additionally, the first-principle density functional theory (DFT) is employed to estimate binding energies of different fluorine-containing compounds. Significant correlations are observed between the total atomic energy of binary fluorides (e.g., of alkali metals, earth metals, and boron group metals) and XPS binding energies. However, for complex compounds like calcium fluorophosphate, correlations with the calculated average atomic total energy are less direct. The review categorizes defluorination methods applied to phosphogypsum as physical, chemical, thermal, and thermal-combined processes, respectively. It introduces neural network machine learning (ML) technology to quantitatively analyze and optimize reported defluorination strategies. Simulation results indicate potential optimizations based on quantitative analyses of process conditions reported in the literature. This review provides a systematic approach to understanding the phosphogypsum composition, fluorine speciation, analytical methodologies, and effective defluorination strategies. The attempts of adopting DFT simulation and quantitative analysis using ML in optimization underscore its potential and feasibility in advancing the industrial phosphogypsum defluorination process. [ABSTRACT FROM AUTHOR]

Tricalcium aluminate (C3A) and tricalcium silicate (C3S) with gypsums play an important role in the hydration of oil well cement. This study aims to assess the influence of C3S and C3A with various gypsums on the hydration of oil well cement at 30, 50, and 80 °C through the analyses of hydration heat evolution by isothermal calorimetry analysis, setting and thickening times, strength, and hydration products by X-ray diffraction. The result reveals that C3A hydrates, in the presence of gypsums, rapidly at 80 °C to produce the C3AH6 phase leading to higher heat evolution. The conversion of AFt to AFm is observed in oil well cement paste at 50 °C. An increase in C3A leads to an increase in compressive strength and a decrease in permeability at 80 °C. An increase of C3S leads to the reduction of cumulative heat evolution and early compressive strength before 28 d. Gypsums shorten cement setting and thickening times opposite to the commonly known retardation effect due to the lower content of C3A and its acceleration on C3S hydration. Dihydrate and hemihydrate gypsums show a greater promotion effect on strength at 30 and 50 °C, while anhydrous gypsum presents a greater enhancing effect at 80 °C. Gypsum increases the permeability while the others show an unobvious effect at 80 °C. [ABSTRACT FROM AUTHOR]

Composite foamed inorganic materials for use as thermal insulation with a reduced thermal conductivity of 0.064 – 0.076 W/(m · K) were developed using industrial silica-containing raw materials. The influence of poreformers and hardeners on the structure, phase formation, and physico-technical properties of foamed materials was studied. It was observed that the combined use of graphite and chalk resulted in a reduction in the density of the materials, while the use of graphite and gypsum and graphite and sodium fluorosilicate led to an increase in the strength of the materials. [ABSTRACT FROM AUTHOR]

The study presents results on the dependence of changes in the rheological characteristics (density and viscosity) of the products of phosphogypsum conversion with sodium carbonate on various factors, including temperature, concentration, sodium carbonate rate, stirring duration, and the temperature of the components mixture. Density was determined using the pycnometric method, and viscosity was measured with a VPJ-2 capillary viscometer. An increase in the concentration of sodium carbonate from 5 to 30%, maintaining it at a constant 105% of the stoichiometric rate, leads to an increase in the density and viscosity of the suspension from 1.0813 to 1.3922 g/cm3 and from 0.78 to 3.30 cP at 20°C, and from 1.0514 to 1.3091 g/cm3 and from 0.31 to 1.86 cP at 80°C, respectively. It was shown that increasing the stirring time from 15 to 120 minutes resulted in an average increase in the density and viscosity of the suspension by 1.02 to 1.08 times and 2.20 to 3.07 times, respectively, at 20°C and 80°C. The study revealed that the temperature of the mixture of phosphogypsum and sodium carbonate in the range of 20-90°C significantly increases the density and viscosity from 1.1922 to 1.2381 g/cm3 and from 1.35 to 2.75 cP, respectively, and from 1.1650 to 1.2033 g/cm3 and from 0.50 to 1.77 cP. With a 30-min conversion of phosphogypsum at varying rates (100–110%) and concentrations (10-30%) of sodium carbonate, the degree of phosphogypsum conversion increased from 84.09 to 97.07%. The optimal degree of phosphogypsum conversion (93.94%) was achieved at a sodium carbonate rate of 105% and a concentration of 20%. Experimental data on the rheological properties of the suspension obtained at various rates and concentrations of sodium carbonate showed the possibility of describing these properties using a linear and logarithmic function, with high correlation coefficient values (R2 = 0.95–0.99). The results provide an assessment of the feasibility of easily pumping the suspension in existing industrial equipment. [ABSTRACT FROM AUTHOR]

In this research, a novel mineral-based composite board was developed using gypsum as a mineral binder and rice straw as a readily available agro-based resource. The study involved two key phases: Phase 1: The preliminary assessment of rice straw-gypsum composite involved integrating different ratios of rice straw into gypsum to examine the influence of rice straw integration on the composite board's performance. The specific proportions used were 90:10%, 80:20%, and 70:30% for rice straw to gypsum. Phase 2: Reinforcement with bacterial nanocellulose fibers. In the subsequent phase, gypsum board composites containing 10%, 20%, and 30% rice straw were further enhanced by the addition of bacterial nanocellulose fibers at 1% and 3% levels. The results indicated a significant influence of rice straw incorporation on the physical and mechanical properties of the panels. The composite boards with 3% bacterial nanocellulose fiber gel exhibited the highest mechanical performance, with values of 13.5 MPa for modulus of rupture, 4650 MPa for modulus of elasticity, and 0.79 MPa for Internal Bond. The study revealed that the adverse effects of rice straw substitution on the mechanical properties and thickness swelling of the panels could be mitigated to a certain extent by incorporating nanocellulose fibers. [ABSTRACT FROM AUTHOR]

To improve the seismic behaviour of cold-formed steel (CFS) walls, a novel infilled CFS wall covered with different wall sheathings (gypsum wallboard, oriented strand board and fibre cement board) was assessed. Four full-scale specimens were tested under cyclic lateral loads to investigate the impacts of the wall sheathings on the seismic performance of the CFS wall. The failure process, failure mode, load–displacement curve, strength degradation, stiffness degradation, energy dissipation, deformation and strain variation of the walls were investigated. The failure modes of the walls were found to be failure of the connections between the CFS frame and the sheathing as well as crushing of the infill material. Compared with a specimen without sheathing, the peak load and lateral stiffness of the walls with sheathing were increased by 1.25–1.72 times, indicating that the sheathings played an important role in the lateral resistance of the wall. An analysis model and formulas for predicting wall lateral stiffness were developed. Comparisons between the calculations and experimental data showed that the proposed theoretical method was able to predict the lateral stiffness of the infilled CFS walls accurately. [ABSTRACT FROM AUTHOR]

Climate change and salt-affected soils detrimentally affect crop production in arid regions. Reclaiming these soils for crops and carbon sequestration can mitigate climate change and enhance food security. A laboratory-scale experiment was conducted on a wheat-maize crop rotation system for three consecutive years to check the effectiveness of organic amendments in reclaiming marginally salt-affected soils, improving soil health, sequestering carbon, and improving food grain production. This study included five treatments namely control (T1), gypsum alone at 100% gypsum requirements (G100), and its combinations with different organic amendments and 50% gypsum requirements (farm manure (FYM+G50), poultry manure (PM+G50), and green manure (GM+G50)) were used. Results indicated that sandy clay loam textured soil showed highest potential for its properties improvement after 45 days, i.e., EC decreased up to 3.9 dS m−1, pH 7.9 and, SOC increase up to 0.25%. After the fallow period, three consecutive years of crop production study indicated up to 39 and 70% increase in wheat and maize yields, respectively, compared to inorganic fertilizer alone. Maximum soil aggregation was noted in treatment with gypsum and farmyard manure application in loam soils (50%). The maximum soil organic carbon accumulation over the whole experiment was recorded in farmyard manure application in combination with gypsum (0.44 g kg−1) in both loam and sandy clay loam soil, while 0.31 g kg−1 in the clay loam soil. Based on the results, it was concluded that reclaiming marginally salt-affected soils enhances food crop production and incorporating manures improves soil through aggregation and carbon sequestration, mitigating climate change. [ABSTRACT FROM AUTHOR]

Background: Lentil is an important legume crop and plays an important role in human nutrition and soil fertility improvement. It contains 57-60% carbohydrate, 24-26% protein, 3.2% fiberand only 1.3% fat with the full complement of amino acids. It is a potential crop for about 10 million hectares of rice-fallow areas of eastern India. This study aimed to standardized sulphur and boron requirements of lentil in Eastern India. Methods: The experiment was conducted in a glass house during 2018-19 and 2019-20 in a factorial completely randomized design with three replications and 16 treatment combinations of sulphur and boron. The treatment combinations were product of 4 levels each of sulphur and boron as 0, 15, 30 and 45 kg ha-1 (0, 0.067, 0.134 and 0.201 g pot-1) and 0, 1, 2 and 3 kg ha-1 (0, 0.004, 0.009 and 0.013 g pot-1), respectively. Lentil grain yield was observed at harvest and sulphur-containing amino acids, as well as seed nutrient content, were analyzed followingstandard operating procedures. Result: Lentil grain yield was enhanced by 1.85 times with a combined application of 45 kg S and 2 kg B ha-1 with a recommended dose of NPK. The sulphur-containing amino acids namely methionine, cystine and cysteine content showed significant improvement with increasing levels of sulphur application however were not significantly affected with boron levels. The protein content in lentil seed increased considerably with application of sulphur levels as compared to boron levels and it was highest with 30 kg S ha-1 + 2kg B ha-1 along with recommended dose of NPK fertilizers. [ABSTRACT FROM AUTHOR]

Background: Groundnut is a prominent oilseed crop in India but its productivity is far below the potential yield because of lack of knowledge along with adoption of enhanced varieties and technologies. The technology gap is a main issue in the production of groundnut in North Eastern zone of Tamil Nadu State in which Cuddalore district falls. A scientific and systematic effort was made to study the impact on yield by assessing the technological gap present in several components of the groundnut cultivation through cluster frontline demonstrations with scientific technologies. Methods: Cluster frontline demonstrations were implemented in groundnut to improve the production potential of improved varieties and new technologies through Krishi Vigyan Kendra. The study with one of its objectives to assess yield and technology gap in groundnut was conducted with 175 demonstrations during the period from 2020-21 to 2022-23 covering seven blocks in an area of 70 hectares in the Cuddalore district following cluster random sampling method. Groundnut varieties VRI 8 and VRI 10 along with improved technologies were demonstrated in the farmer’s field by providing necessary critical inputs along with seed drill sowing. Result: There resulted 53.34 per cent rise in yield as observed in demonstration plots over farmers’ practices in groundnut. The study revealed that in groundnut, the average extension gap of 13.95 q/ha, the average technology gap of 14.52 q/ha and the average technology index of demonstrations is 26.41 per cent. The higher average net returns (Rs. 149758/ha) were recorded in the demonstration plot (BCR 2.4) compared to the farmers’ plot. The sustainability yield index (SYI) and Sustainability Value Index (SVI) in demo plots are higher consistently than in farmers’ plots mainly due to the effect of cluster frontline demonstrations with the proper application of inputs/technologies viz., VRI 8 and VRI 10 varieties, treatment of seed by using bio-fertilizers, biocontrol agents, a test of soil based nutrient management, application of TNAU crop booster groundnut rich and gypsum application. [ABSTRACT FROM AUTHOR]

This paper addresses the imperative need for understanding the mechanical properties of clay brick masonry with gypsum mortar, the primary construction material in Persian historical buildings, to facilitate accurate restoration efforts. Given the constraints of heritage preservation, destructive tests on large-scale specimens are unfeasible. As a viable alternative, this research employs scaled-down specimens to investigate the flexural strength. For the first time, Persian clay brick masonry with gypsum mortar assemblages have been tested at three scales of 1:2, 1:4 and 1:6 to determine the flexural strength. The paper introduces new relationships between the flexural strength of brick masonry and brick size. Furthermore, it establishes a correlation between the flexural strength of the brick masonry specimens and the flexural strengths of both the brick and the gypsum mortar. Additionally, some specimens incorporate cement mortar instead of gypsum mortar for result comparison. The obtained results reveal the profound influence of mortar type and thickness, along with brick dimensions, on flexural strength. The flexural strength of brick masonry increases with decreasing brick size. By reducing the size of bricks, the ratio of compressive strength to flexural strength decreases, offering key insights for restoration efforts. [ABSTRACT FROM AUTHOR]

Calcium sulfoaluminate belite (CSAB) cement has gained prominence as a viable environmentally friendly substitute for conventional portland cement (PC). The current study investigates the relative performance of expansive and nonexpansive CSAB cement-based concretes, and PC-based concretes when subjected to chloride-rich conditions. Multiple testing methodologies, including surface resistivity measurements, chloride migration, rapid chloride penetration, long-term bulk diffusion, and water sorptivity, were employed to assess the durability of these concrete systems. Surface resistivity measurements indicated that CSAB systems exhibited significantly higher resistivity when compared with PC-based counterparts. Increased resistivity in CSAB systems was influenced by the conductivity of the pore solution, emphasizing that the formation factor provides a more accurate representation of the pore structure within the system. The expansive and nonexpansive CSAB cement–based concrete outperformed PC-based concrete in migration-based tests and rapid chloride penetration test (RCPT). In contrast, the CSAB and PC systems demonstrated similar performance in the long-term bulk diffusion-based test. Although CSAB systems exhibit finer pore structures than PC-based counterparts, their performance in chloride-rich environments is affected by their reduced binding capacity. The study emphasizes that the conclusions drawn from accelerated tests and resistivity measurements of CSAB cement–based concrete must be cautiously interpreted because these results may not indicate real-world performance. [ABSTRACT FROM AUTHOR]

This paper investigates the tensile behaviors and self-healing of engineered cementitious composite (ECC) under sulfate wet–dry cycles to reflect the durability. Four pretensile strain levels of 0%, 1%, 1.5%, and 2% were designed. The uniaxial tensile test, three-point bending test, and single-crack tensile test were performed, along with the microscopic characterizations of scanning electron microscope (SEM) and X-ray diffraction (XRD). The results indicated that the sulfate wet–dry cycle exposure had a positive effect on the tensile strength and initial cracking strength of the uncracked ECC, while that was negative on the tensile strain capacity. The insufficient margin of the σoc/σcr and Jb′/Jtip indices explained the lower tensile strain. The tensile strength and initial cracking strength of the cracked ECC with 1% pretensile strain surpassed those of the uncracked ECC after undergoing 80 sulfate wet–dry cycles (80 C), while that did not hold for the other cracked ECCs. All the cracked ECCs showed a similar tensile strain after undergoing 80 C. The crack with a width of less than 100 μm achieved complete self-healing. The self-healing products of ECC under sulfate wet–dry cycle exposure may comprise of calcium (alumino) silicate hydrate [C-(A)-S-H] gel, calcite, ettringite, and gypsum. The current findings could offer reference points for applying ECC use in coastal regions. [ABSTRACT FROM AUTHOR]

Soda-saline soils pose significant challenges to agricultural productivity, particularly in regions like the foothill plain of the Ili Alatau in southeast Kazakhstan. In this study, we examined the effectiveness of different ameliorants, including phosphogypsum, elemental sulfur, and sulfuric acid, in reclaiming soda-saline soils and enhancing crop yields. The study was conducted under real climatic and production conditions at the "Amiran" LLP farm. Using a randomized complete block design, we assessed the impact of these ameliorants on soil composition and alfalfa yield over two cutting cycles. The experiment involved the application of phosphogypsum, elemental sulfur, and sulfuric acid to designated plots within the farm, each covering an area of 15m2. Soil samples were collected before and after treatment to assess changes in soil composition and salinity. Alfalfa, a resilient perennial crop, was selected for cultivation due to its tolerance to adverse soil conditions. Our findings reveal that all tested ameliorants successfully neutralized the toxic environment of soda-saline soils, resulting in improved soil conditions and increased crop productivity. Phosphogypsum treatment led to a reduction in bicarbonate and carbonate ions, an increase in sulfate ion concentration, and improved soil structure. Elemental sulfur incubation decreased bicarbonate and carbonate ions, further reducing absorbed sodium levels and enhancing soil fertility. Sulfuric acid treatment provided rapid results in reducing alkalinity and increasing sulfate ion concentration, leading to significant improvements in soil quality and crop yield. However, the reclamation of soda-saline solonetzes presented challenges related to soil heterogeneity and poor water permeability. To address these challenges, we recommend the implementation of mechanical destruction of the solonetz soil horizon and deep soil loosening, accompanied by the addition of ameliorants. In conclusion, our study demonstrates the potential of phosphogypsum, elemental sulfur, and sulfuric acid as effective ameliorants for reclaiming soda-saline soils and improving agricultural productivity in challenging environments. By adopting recommended reclamation strategies, farmers can overcome soil limitations and achieve sustainable crop production in regions affected by soda-saline soil degradation. [ABSTRACT FROM AUTHOR]