CaSO4 Research Articles

Recovery of residual polyamide (PA12) from polymer powder bed fusion additive manufacturing process through a binder jetting process

PurposeThis study aims to propose the reuse of PA12 (powder) in another AM process, binder jettiinng, which is less sensitive to the chemical and mechanical degradation of the powder after multiple cycles in the laser system.Design/methodology/approachThe experimental process for evaluating the reuse of SLS powders in a subsequent binder jetting process consists of four phases: powder characterization, bonding analysis, mixture testing and mixture characteristics. Analyses were carried out using techniques such as Fourier Transform Infrared Spectroscopy, scanning electron microscopy, thermogravimetric analysis and stress–strain tests for tension and compression. The surface roughness, color, hardness and density of the new mixture were also determined to find physical characteristics. A Taguchi design L8 was used to search for a mixture with the best mechanical strength.FindingsThe results indicated that the integration of waste powder PA12 with calcium sulfate hemihydrate (CSH) generates appropriate particle distribution with rounded particles of PA12 that improve powder flowability. The micropores observed with less than 60 µm, facilitated binder and infiltrant penetration on 3D parts. The 60/40 (CSH-PA12) mixture with epoxy resin postprocessing was found to be the best-bonded mixture in mechanical testing, rugosity and hardness results. The new CSH-PA12 mixture resulted lighter and stronger than the CSH powder commonly used in binder jetting technology.Originality/valueThis study adds value to the polymer powder bed fusion process by using its waste in a circular process. The novel reuse of PA12 waste in an established process was achieved in an accessible and economical manner.

Abstract 2062: Engineering Extracellular Matrix Cues To Study The Progression Of Endothelial To Mesenchymal Transition

Endothelial-mesenchymal transition (EndoMT) is a biological process in which vascular endothelial cells (ECs) acquire a mesenchymal identity that give rise to lineages like fibroblasts and smooth muscle-like cells. Pathologically, EndoMT is involved in the progression of cardiovascular diseases such as atherosclerosis, in which ECs give rise to smooth muscle-like cells within the plaque. However, there is essentially a dearth of knowledge of how the biochemical and biomechanical cues from the extracellular matrix (ECM) milieu directly influence the progression of EndoMT. To address the limited knowledge of ECM effects on EndoMT, we aim to develop a 3D tissue engineered model with independently tunable biochemical and biomechanical cues, including stiffness, stress relaxation rate and ECM composition to study EndoMT progression in 3D. Alginate hydrogels were prepared at 2% w/v final concentration and crosslinked using calcium sulfate and different concentrations. Human primary coronary artery endothelial cells (HCAECs, Lonza) were formed into spheroids and then co-encapuslated with fibroblasts in the alginate hydrogels for 7 days. EndoMT was induced by using media with no supplements such as VEGF and bFGF (that inhibit EndoMT) and using TGFb treatment. We successfully fabricated a family of alginate hydrogels with different mechanical and viscoelastic properties. HCAEC spheroids survived well in the 3D alginate hydrogel system and actively interacted with the fibroblasts in the hydrogels. Additionally, we observed viscoelasticity dependent migration of ECs from the spheroid into the alginate hydrogel and vessel like tube formation in the 3D model. Lastly, we quantified higher expression of the mesenchymal marker, SM22, in ECs in slow relaxing hydrogels, pointing towards viscoelasticity dependent progression of EndoMT. These results underscore the importance of mechanical factors such viscoelasticity in addition to stiffness in progression of diseases like atherosclerosis. Future work involves performing transcriptomics analysis to uncover the mechanism behind viscoelasticity dependent EndoMT progression.

Comparative Studies of Bone Graft and Orthobiologics for Foot Ankle Arthrodesis: A Critical Review.

Graft materials available to supplement hindfoot and ankle arthrodesis procedures include autologous (autograft) or allogeneic bone graft (allograft) but also bone graft substitutes such as demineralized bone matrix, calcium sulfate, calcium phosphate, and tricalcium phosphate/hydroxyapatite. In addition, biologic agents, such as recombinant human bone morphogenetic protein-2 or recombinant human platelet derived growth factor-BB (rhPDGF-BB), and preparations, including platelet-rich plasma or concentrated bone marrow aspirate, have been used to facilitate bone healing in ankle or hindfoot arthrodesis. The purpose of this review was to summarize the available clinical evidence surrounding the utilization and efficacy of the above materials and biological agents in ankle or hindfoot arthrodesis procedures, with emphasis on the quality of the existing evidence to facilitate clinical decision making.

Effect of spacer on mass transfer coefficient and calcium sulfate scaling phenomena in reverse osmosis desalination

Inorganic material (scale) precipitation on reverse osmosis (RO) membranes is a serious issue in plants because performance recovery via cleaning is challenging, and the replacement expenses are enormous. This study investigated the calcium sulfate scaling phenomena on membranes using a flat membrane cell with a spacer to model a spiral wound-type RO element. Subsequently, the mass transfer coefficient of the flat membrane cell with the spacer and the convergent value of permeate flux due to solute precipitation were determined. The dimensionless equation for the mass transfer coefficient of the cell with the spacer could be expressed using the dimensionless equation for the mass transfer coefficient of a flat membrane cell without a spacer. The behavior in permeate flux due to the precipitation of calcium sulfate on the RO membrane of the cell with the spacer was analyzed based on the scaling-based critical flux and scaling index, which discriminate scale precipitation. Finally, scale precipitation experiments were conducted by varying spacers and the operating conditions of pressure, solute concentration, temperature, and Reynolds number; the permeate flux was confirmed to converge to the scaling-based critical flux, and the scaling index could discriminate the operating condition area of scale precipitation.

Effects of food waste biogas residue composting on soil aggregates and its organic matter content in relocation site

Understanding the effects of food waste biogas residue composting and chemical amendments on soil aggregates composition of different particle sizes, stability, and organic matter distribution in relocation sites could provide primary data for improving soil quality and land utilization of food waste biogas residue composting. We analyzed the characteristics of soil aggregates distribution, stability of aggregates, and organic matter content in different particle sizes under treatments with different application amounts of food waste biogas residue composting, chemical amendments (β-cyclodextrin, calcium sulfate and ferric oxide were mixed at a mass ratio of 1:1:1), and control (100% soil). The results showed that 20% (soil: biogas residue composting=8:2) and 30% (soil: biogas residue composting =7:3) biogas residue composting significantly decreased the micro-aggregates content with the particle size of <0.106 mm and increased the large aggregates content with the particle size of 0.5-1.0 mm. All treatments significantly increased large aggregates content with the particle size of ≥2.0 mm, soil aggregate structure content, and mean weight diameter, but reduced the percentage of aggregate destruction. Among all the treatments, the effect of mixes application of 20% biogas residue composting and chemical amendments was the best. Biogas residue composting treatments significantly affected the distribution of organic matter in soil aggregates, with the strongest effect under 30% biogas residue composting treatment. Biogas residue composting treatments significantly increased soil organic matter content in all aggregates, with the maximal increase of organic matter content in soil micro-aggregates with the particle size of 0.106-0.25 mm. In conclusion, biogas residue composting could increase organic matter content of soil aggregates in different particle sizes, promote the formation of large soil aggregates, and improve the stability of aggregation. Specifically, the mixed application of biogas residue composting and chemical amendments performed better on soil improvement in relocation site.

Theoretical study of adsorption of sodium, lithium, magnesium and calcium chloride and sulfate salts by pure and Sc-doped B12N12 nanocages and pure boron nitride nanosheet

High concentrations of water-soluble chloride and sulfate salts may cause adverse effects to humans and plants. Boron nitride (BN) nanostructures seem able to remove these water-soluble salts. In addition, Li+, Mg2+, Ca2+, and Na2+ interactions with BN nanostructures have received much attention in fabricating high-performance metal-ion batteries. Accordingly, this study investigated the adsorption of chloride and sulfate salts of Li, Mg, Ca, and Na on pristine and scandium (Sc)-doped B12N12 nanocages and pure BN nanosheet through DFT calculations. Optimizing the structures at the B3LYP/6-31 g (d, p) and M062X/6-311 g (d, p) computational levels indicated very exothermic chemisorption of chloride and sulfate salts on the pure and Sc-doped B12N12 nanocages. The B12N12-LiCl and Sc@B11N12-LiCl complexes showed the highest negative adsorption energies of −26.33 and −57.30 kcal/mol among the chloride salts. The B12N12-MgSO4 and Sc@B12N12-MgSO4 complexes showed the highest adsorption energies of −69.27 and −102.70 kcal/mol among the sulfate salts. Studying the effect of the adsorption process on the electronic properties of the B12N12 nanocage showed a reduction in the energy gap upon the adsorption of all salts on the pure B12N12 nanocage with the lowest energy gap of 3.98 eV for B12N12-MgSO4. The adsorption energies of the individual salts and their complexes on the B12N12 nanosheet at the B3LYP/6-311 g (d, p) level imply the occurrence of physisorption. A significant reduction was observed in the energy gap by adsorbing the salts on the BN nanosheet. Adsorbing CaSO4 and MgSO4 on the BN nanosheet caused the largest variation of 1.71 and 1.56 eV in the energy gap, respectively. The promising results of our study highlight the potential application of BN nanostructures in the removal of various soluble salts and the fabrication of metal-ion batteries.

Novel injectable composite incorporating denosumab promotes bone regeneration via bone homeostasis regulation

Repair of large bone defects remains to be clinically challenging, yet current bone repair strategies focus on optimizing the osteogenic capacity of bone grafts, while the role of osteoclasts in bone regeneration has been largely ignored. Herein, we designed a injectable self-curing bone grafting paste capable of regulating both anabolic/catabolic activities during bone healing by immobilizing the RANKL inhibitor denosumab on dermal-derived extracellular matrix (ECM) microfibres, which were then incorporated into an injectable paste via a hydration reaction between β-tricalcium phosphate (β-TCP), monocalcium phosphate monohydrate (MCPM) and calcium sulfate hemihydrate (CSH). The incorporation of ECM microfibres not only serves as a sustained-release denosumab carrier to inhibit osteoclastogenesis but also improves the mechanical properties of the resulting composite by increasing the interaction between the organic and inorganic phases. In vitro, calcium supply from the composite along with ECM enhanced osteogenic differentiation of BMSC while release of denosumab effectively inhibits osteoclast fusion and alleviate osteoclastic activity. In vivo, it was observed that CSH/CP@ECM-Deno significantly reduced the number of osteoclasts, slowed down the process of bone resorption, and accelerated collagen deposition to promote new bone generation. These results suggest that modulation of osteoclastogenesis by interfering with bone homeostasis may be an effective bone repair strategy.

Development of a slow-release CO2 absorbent material for alkaline activation of persulfate oxidation of TCE and CO2 capture

Control of carbon dioxide (CO2) emission during chemical oxidation processes of organic-chemical contaminated sites has become a challenge. In this study, a novel slow-release CO2 absorbent material (SCAM) was developed for a slow release of Ca2+ and OH–, which were used for CO2 capture, pH adjustment, and alkaline activation of persulfate (PS) oxidation for trichloroethylene (TCE) degradation. The SCAM was produced using basic oxygen furnace slag (BOFs) and calcium sulfate hemihydrate (CSH) as the components for granulation and modification. Batch experiments were conducted to determine the optimal mass ratio of BOFs to CSH and evaluate CO2 capture capacity and SCAM performance. An increase in BOFs proportion led to a higher CO2 capture capacity, with the maximum capture amount reaching 156 g CO2/kg SCAM. An excessive addition of BOFs resulted in an overly alkaline pH value (pH = 12.4), causing the diminished PS oxidation efficiency. The optimal mass ratio of BOFs to CSH (1 to 1) could capture produced CO2 after TCE oxidation without inhibiting PS oxidation. The SCAM could serve as the catalyst and activate PS oxidation, resulting in 93.1 % of TCE oxidation (initial TCE concentration = 2.32 mM) and 95.4 % of CO2 emission reduction due to the formation of CaCO3 precipitates under alkaline conditions. Produced sulfate and hydroxyl radicals confirmed the PS oxidation of TCE using SCAM as an activator. The developed SCAM is a green catalyst for PS oxidation and it is also an effective CO2 absorbent. SCAM can reduce CO2 emission due to the formation of CaCO3 precipitates under alkaline conditions. The released OH– could also prevent the acidification problem caused by the production of sulfuric acid through PS decomposition.

Synthesis of calcium sulfate hemihydrate whiskers from high-purity salt gypsum in a glycerol–water solution at atmospheric pressure

Calcium sulfate hemihydrate whiskers (CSHWs) were prepared from high-purity salt gypsum in a glycerol–water system. The effects of the glycerol/water ratio, reaction temperature, reaction time, and stirring speed on the crystal morphology of the CSHWs were investigated. Results showed that the average length and average length/diameter (L/D) ratio of the CSHWs first increased and then decreased as the glycerol/water ratio, reaction time, and stirring speed were increased, but they continued to gradually increase with increasing reaction temperature. The CSHWs had the highest L/D ratio and smooth surfaces—with an average length of 42.91 μm, an average diameter of 0.72 μm, and an average L/D ratio of 55—when the preparation conditions were a glycerol/water ratio of 2.0, a reaction temperature of 100 °C, a reaction time of 2.0 h, and a stirring speed of 300 rpm. This study provides a feasible idea for the treatment of salt gypsum, which achieves high value-added utilization of salt gypsum as well as the elimination of solid waste.

Acid leaching technology for post-consumer gypsum purification

Background Contaminants and water-soluble salts present in mechanically recycled gypsum from refurbishment and demolition (post-consumer) plasterboard waste limit its use as a secondary raw material in plasterboard manufacturing. This research addresses this limitation, developing a novel acid leaching purification technology combined with an improved mechanical pre-treatment for post-consumer gypsum valorization. Methods Laboratory-scale acid leaching purification was performed with a borosilicate beaker, hot plate, and overhead stirrer. Stuccos were produced after calcination of gypsum at 150 °C for 3 hours. Samples were characterized through X-ray fluorescence, X-ray diffraction, thermal gravimetric analysis, scanning electron microscopy and particle size analysis. Results Acid leaching at 90 °C for 1 h using a 5 wt% sulfuric acid solution was revealed to be the optimum purification conditions. Stuccos produced from purified gypsum under optimum conditions had similar initial setting times to that of a commercial stucco but with higher water demand, which could be reduced by optimizing the calcination conditions. A magnesium-rich gypsum was precipitated from the wastewater. Conclusions Purified post-consumer gypsum with &gt; 96 wt% chemical purity and calcium sulfate dihydrate content was produced. The research recommends acid neutralization prior filtration, use of gypsum particles &lt; 2 mm in size, and stirring speed of 50 rpm to reduce the economic and environmental impacts of the acid leaching purification process at industrial scale. The magnesium-rich gypsum could potentially be marketed as soil fertilizer.

Carbonation resistance of recycled fine aggregate concrete reinforced by calcium sulfate whiskers

This study investigates mechanical and carbonation resistance tests conducted on Recycled Fine Aggregate Concrete (RFAC) with three different Recycled Fine Aggregate (RFA) replacement rates and four calcium sulfate whisker (CSW) contents, and investigates the effects of RFA replacement rate and CSW content on the mechanical properties of RFAC and the carbonation resistance of RFAC with calcium sulfate whiskers at different ages of carbonation. The microstructure of CSW-modified RFAC was observed and analyzed by SEM electron microscopy to explore further enhancement and toughening mechanisms of CSW in RFAC, as well as the optimal content of CSW in RFAC. In addition, the carbonation depth of recycled concrete with calcium sulfate beard is modeled based on a quadratic fitting formulation. The test results show that the mechanical properties and carbonation resistance of RFAC would decrease with the increase of the RFA replacement rate. Incorporating CSW can effectively improve the mechanical properties and carbonation resistance of RFAC. At 60 % RFA substitution, CSW at 2 % content has the most significant effect on the mechanical properties and carbonation resistance of RFAC. Microscopic analysis shows that CSW has a bridging effect at the micro-cracks in the concrete matrix, preventing the creation and expansion of micro-cracks in the concrete matrix, thus improving RFAC mechanical properties of RFAC and resistance to carbonation. The predicted results of the carbonation depth model which are constructed from the test data coincide with the results. We can use them to predict and analyze the carbonation depth of the carbonation resistance of recycled concrete.

Role of STIMULAN in chronic osteomyelitis-A randomised blinded study on 95 patients comparing 3 antibiotic compositions, bead quality, forming & absorption time

IntroductionChronic Osteomyelitis is a well-known clinical entity affecting patients holistically and presents with multiple treatment challenges. Local antibiotic delivery with biodegradable drug carriers has shown promising results. Materials and methodsProspective multicenter study performed at 2 centers from November 2021 to January 2023 on 95 osteomyelitis patients treated with surgical debridement & STIMULAN™ for local antibiotic delivery. Patients were randomized into 3 groups. Authors compared antibiotic combinations, bead quality, bead setting, and resorption time for calcium sulfate beads- STIMULAN™. Additionally, organisms isolated, WBC Turnover time, Hypersensitivity Reactions, Recurrence, and Revision Rates were documented. Results95 patients underwent surgical debridement and STIMULAN™ bead application for chronic osteomyelitis. The proximal 1/3rd tibia was commonly affected. The most common symptoms were sinus and pus discharge in 96.84 % & 86.31 % of patients respectively (p < 0.001). Staphylococcus aureus & MRSA were isolated in 37.8 % & 29.4 % of the patient's wound culture respectively. Bead setting time in Descending order was Group 3 > Group 2 > Group 1 (p < 0.001). Bead setting first in Group 1 followed by Group 3 & 2. On compression, Group-1 beads withstood maximum compression forces & had smooth even bead surfaces. On radiographs, 1/3rd bead volume in ascending order was Group 3 > Group 2 > Group 1 (p < 0.001). 2/3rd reduction in ascending order was Group 3 > Group 2 > Group 1. Complete bead absorption was earliest seen in Group 3 followed by Group 2 & Group 1 (p < 0.001). Recurrence in 2 patients (Group 2) at 6 weeks. Revision rate: 2.10 %. There were no incidences of hypersensitivity. Suture removal was done at 16 ± 2 days. ConclusionSTIMULAN™ combination with tobramycin, vancomycin, and gentamycin is stable, and forms uniform beads with predictable drug elution & bead resorption with negligible side effects. A mixture with higher liquid content sets later, forms softer beads, and resorbs earlier.

Improved length of calcium sulfate crystal seeds and whiskers via ball milling and hydration treatment

Elucidating the effect of growth periods on the quality of calcium sulfate whiskers (CSWs) prepared from calcium sulfate dihydrate (DH) is imperative. Herein, crystal seeds and whiskers were prepared from DH in a water–glycerol system. Longer whiskers were obtained from crystal seeds prepared via hydration of DH for 30 s than via ball milling for 5 min followed by hydration for 20 s. The attachment of cetyltrimethyl ammonium bromide and glycerol additives to the whisker tops promoted whisker growth. The whisker sponges exhibited good thermal barrier properties and compression cycle stability.

Influence of free calcium sulfate levels on the early hydration of sulfate-rich belite sulfoaluminate clinkers: A comparative study with anhydrite and gypsum

In the present study, belite sulfoaluminate (BSA) clinkers containing varying levels of free calcium sulfate (f-CaSO4)—specifically 0 %, 5 %, and 10 %—were synthesized. These clinkers were subsequently mixed with anhydrite and gypsum for comparative analysis. Utilizing a range of analytical techniques such as isothermal calorimetry, X-ray diffraction (XRD), and thermogravimetric analysis (TGA), the early hydration process and the constitution of hydration products were systematically investigated. The experimental data reveal that sulfate-rich BSA clinkers demonstrate enhanced hydration activity, as well as superior early compressive strength. As the f-CaSO4 content escalates, there is a corresponding increase in the cubic crystal sulfoaluminate within the BSA clinkers. This compositional shift has a beneficial impact on both the initial and final setting times, thereby enhancing the 3-day compressive strength. Contrary to ordinary BSA cement clinkers, those rich in sulfate retard the dissolution rate of external gypsum. It is noteworthy that anhydrite, possessing a solubility greater than gypsum, exerts a more pronounced acceleration effect on the early hydration process of sulfate-rich BSA clinkers.

Comparison of different bone substitutes in the repair of rat calvaria critical size defects: questioning the need for alveolar ridge presentation.

This study aimed to evaluate the effectiveness of biomaterials in bone healing of critical bone defects created by piezoelectric surgery in rat calvaria. Histomorphologic analysis was performed to assess bone regeneration and tissue response. Fifty animals were randomized into five groups with one of the following treatments: Control group (n = 10), spontaneous blood clot formation with no bone fill; BO group (Bio-Oss, Geistlich Pharma; n = 10), defects were filled with bovine medullary bone substitute; BF group (Bonefill, Bionnovation; n = 10), defects were filled with bovine cortical bone substitute; hydroxyapatite group (n = 10), defects were filled with hydroxyapatite; calcium sulfate group (n = 10), defects were filled with calcium sulfate. Five animals from each group were euthanized at 30 and 45 days. The histomorphometry calculated the percentage of the new bone formation in the bone defect. All data obtained were evaluated statistically considering P < .05 as statistically significant. The results demonstrated the potential of all biomaterials for enhancing bone regeneration. The findings showed no statistical differences between all the biomaterials at 30 and 45 days including the control group without bone grafting. In conclusion, the tested biomaterials presented an estimated capacity of osteoconduction, statistically nonsignificant between them. In addition, the selection of biomaterial should consider the specific clinical aspect, resorption rates, size of the particle, and desired bone healing responses. It is important to emphasize that in some cases, using no bone filler might provide comparable results with reduced cost and possible complications questioning the very frequent use of ridge presentation procedures.

NOVEL APPROACH: PERCUTANEOUS INJECTION OF BONE-SUBSTITUTE (CERAMENT-GTM) TO AID BONY HEALING IN STIFF NONUNITED COMPLEX OPEN TIBIAL FRACTURES

IntroductionTreatment of non-union in open tibial fractures Gustilo-Anderson(GA)-3A/3B fractures remains a challenging problem. Most of these can be dealt using treatment methods that requires excision of the non-union followed by bone grafting, masquelet technique, or acute shortening. Circular fixators with closed distraction or bone transport also remains a useful option. However, sometimes due to patient specific factors these cannot be used. Recently antibiotic loaded bone substitutes have been increasingly used for repairing infected non-unions. They provide local antibiotic delivery, fill dead space, and act as a bone conductive implant, which is resorted at the end of a few months. We aimed to assess the outcome of percutaneous injection of bone substitute while treating non-union of complex open tibial fractures.Materials &amp; MethodsThree cases of clinical and radiological stiff tibial non-union requiring further intervention were identified from our major trauma open fracture database. Two GA-3B cases, treated with a circular frame developed fracture-related-infection(FRI) manifesting as local cellulitis, loosened infected wires/pins with raised blood-markers, and one case of GA-3A treated with an intramedullary nail. At the time of removal of metalwork/frame, informed consent was obtained and Cerament-GTM(bone-substitute with gentamicin) was percutaneously injected through a small cortical window using a bone biopsy(Jamshedi needle). All patients were allowed to weight bear as tolerated in a well-fitting air-cast boot and using crutches. They were followed up at 6 weekly intervals with clinical assessment of their symptoms and radiographs. Fracture union was assessed using serial radiographs with healing defined as filling of fracture gap, bridging callus and clinical assessment including return to full painless weight bearing.ResultsFollow-up at 6 months showed all fractures had healed with no defect or gaps with evidence of new trabecular bone and significant resorption of Cerament-GTM at final follow-up. There was no evidence of residual infection with restoration of normal limb function. Fractures with no internal fixation showed a mild deformity that had developed during the course of the healing, presumed due to mild collapse in the absence of fixation. These were less than 10 degrees in sagittal and coronal planes and were clinically felt to be insignificant by the patients.ConclusionsCerament-G's unique combination of high dose antibiotics and hydroxy apatite matrix provided by calcium sulphate might help provide an osteoconductive environment to allow these stiff non-unions to heal. The matrix appears to provide a scaffold-like structure that allows new bone in-growth with local release of antibiotics helping reduce deep-seated infections. The final deformation at fracture site underlines the need for fixation- and it is very unlikely that this technique will work in mobile nonunions. Whilst similar fractures may heal without the use of bone substitute injections, the speed of healing in presence of significant fracture gap suggests the use of these bone substitutes did help in our cases. Further studies with a larger cohort, including RCTs, to evaluate the effectiveness of this technique compared to other methods are needed.

Homopolymers and copolymers with iminodiacetic acid chelating units for scale inhibition

Novel homopolymer and copolymer scale inhibitors with iminodiacetic acid chelating units were synthesized for inhibiting calcium carbonate and calcium sulfate precipitation. Static scale inhibition tests of SI-1 demonstrated excellent performance, with inhibition performance of 83 % at a concentration of 30 mg/L for CaCO3 and >99 % at a concentration of 8 mg/L for CaSO4. These novel inhibitors surpassed the performance of a commercially available industrial scale inhibitor, 2-phosphonobutane-1,2,4-tricarboxylic acid. The homopolymer significantly altered CaCO3 and CaSO4 crystal structures and reduced crystal size at low concentrations. The primary mechanism of inhibition appears to be a two-fold effect: strong and specific complexation between the iminodiacetic acid chelating units and free Ca2+ ions, coupled with the adsorption of the polymers on the crystal surfaces. These promising scale inhibitors offer a potential replacement for phosphorus-containing compounds currently used in industrial applications.

A Bioactive Degradable Composite Bone Cement Based on Calcium Sulfate and Magnesium Polyphosphate.

Calcium sulfate bone cement (CSC) is extensively used as a bone repair material due to its ability to self-solidify, degradability, and osteogenic ability. However, the fast degradation, low mechanical strength, and insufficient biological activity limit its application. This study used magnesium polyphosphate (MPP) and constructed a composite bone cement composed of calcium sulfate (CS), MPP, tricalcium silicate (C3S), and plasticizer hydroxypropyl methylcellulose (HPMC). The optimized CS/MPP/C3S composite bone cement has a suitable setting time of approximately 15.0 min, a compressive strength of 26.6 MPa, and an injectability of about 93%. The CS/MPP/C3S composite bone cement has excellent biocompatibility and osteogenic capabilities; our results showed that cell proliferation is up to 114% compared with the control after 5 days. After 14 days, the expression levels of osteogenic-related genes, including Runx2, BMP2, OCN, OPN, and COL-1, are about 1.8, 2.8, 2.5, 2.2, and 2.2 times higher than those of the control, respectively, while the alkaline phosphatase activity is about 1.7 times higher. Therefore, the CS/MPP/C3S composite bone cement overcomes the limitations of CSC and has more effective potential in bone repair.

Materials analysis in three paintings of Thomas Gainsborough (1727–1788) by portable X-ray fluorescence

Three paintings of Thomas Gainsborough (1727–1788), one of the most influential English portrait painters of the late 18th century, from the collection of the Museu de Arte de São Paulo (MASP) - “Francis Rawdon” (1783–1784), “Portrait of Mrs. John Bolton” (1770), and “Drinkstone Park” (1747) - were investigated using portable X-ray fluorescence (pXRF), employing a W tube anode and an XR-100CR detector. These artworks represent the only paintings by Thomas Gainsborough located in the southern hemisphere. Through an analysis of the behavior of X-ray line net areas for all identified elements in various regions of the oil paintings, it was observed that XRF accurately identified the original materials: Lead White, Calcium Carbonate, Calcium Sulfate, Bone Black, Ivory Black, Yellow Iron Oxide, Prussian Blue, Vermillion, Red Iron Oxide, Umber, and Sienna Earth. Additionally, certain regions exhibited the presence of 19th century pigments: Zinc White, Cobalt Blue, and Chrome Yellow, indicating areas that had undergone restoration. The findings presented in this study align closely with results obtained from other investigations into paintings by Thomas Gainsborough.

Application of the Industrial Byproduct Gypsum in Building Materials: A Review.

The industrial byproduct gypsum is a general term for byproducts discharged from industrial production with calcium sulfate as the main ingredient. Due to the high number of impurities and production volume, the industrial byproduct gypsum is underutilized, leading to serious environmental problems. At present, only desulfurization gypsum and phosphogypsum have been partially utilized in cementitious materials, cement retarders, etc., while the prospects for the utilization of other byproduct gypsums remain worrying. This paper mainly focuses on the sources and physicochemical properties of various types of gypsum byproducts and summarizes the application scenarios of various gypsums in construction materials. Finally, some suggestions are proposed to solve the problem of the industrial byproduct gypsum. This review is informative for solving the environmental problems caused by gypsum accumulation.