[A brief history of the use of Gypsum in orthopedics].

Humans processed gypsum for their everyday use at least 7000 years ago. They have been using fixed limb methods for fracture treatment for nearly 5000 years. Hippocrates recognized the importance of the splint and the "roller bandage" for fracture treatment, and made the bandage hard by adding wax, pitch, lard or resin to the multi-layer cloth bandage, but not gypsum. Arabian physician El Zahrawi (936 -1013) also described a clay glue mixture, and flour and egg white as fracture fixation materials. From 970, Persian physician Muwafak used gypsum as the exclusive material for fracture fixation. The rudimentary form of modern plaster bandages was developed in the mid-19th century and spread widely after that, using methods from the Russian Pyrogov by soaking canvas in a gypsum slurry and Dutchman Massson wrapped gypsum powder in cotton cloth strips.

Feasibility and Preliminary Efficacy of α-Calcium Sulfate Hemihydrate in Socket Preservation: Protocol for a Pilot Randomized Controlled Trial.

BACKGROUND: Tooth extraction procedures often lead to bone resorption, which can have adverse effects on the dimensions of the alveolar ridge. Research has shown that socket preservation techniques using bone graft substitutes can effectively minimize early bone loss in such cases. α-calcium sulfate hemihydrate (α-CSH) has garnered significant attention as a potential bone graft material due to its favorable properties, including osteoconductivity, angiogenic potential, and biocompatibility. Considering these facts, we developed a preliminary protocol for applying α-CSH in addressing alveolar bone loss following tooth extraction. OBJECTIVE: This research's general objective is to evaluate the feasibility and initial effectiveness of α-CSH as bone-inducing graft material for socket preservation after tooth extraction. METHODS: This preliminary clinical trial will involve 30 fresh extraction sockets from individuals aged 18-35 years. The participants will be divided into 2 groups: one group will receive α-CSH graft material after tooth extraction for socket preservation, while the other group will not receive any graft material. Throughout the study, the participants will be closely monitored for safety measures, which will include clinical examinations, radiographic imaging, and blood tests. Radiographic imaging will be used extensively to assist the progress of bone formation. RESULTS: The study commenced enrollment in August 2022 and is scheduled to conclude post assessments and analyses by the end of 2023. The results of the study are anticipated to be accessible in late 2024. CONCLUSIONS: This clinical study represents the initial investigation in humans to assess the feasibility and efficacy of α-CSH in alveolar bone regeneration. We hypothesize that the inclusion of α-CSH can greatly expedite the process of bone formation within fresh sockets, resulting in a swift restoration of bone height without the disadvantages associated with harvesting autogenous bone graft. TRIAL REGISTRATION: Indonesia Registry Center INA-D02FAHP; https://tinyurl.com/2jnf6n3s. INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID): DERR1-10.2196/49922.

Synergistic effects of Co-pyrolysis on the immobilization and transformation of lead (Pb), chromium (Cr), nickel (Ni), and fluorine (F) in phosphogypsum-biomass mixtures.

Co-pyrolysis of biomass with phosphogypsum (PG) presents an effective strategy for facilitating the recycling of PG resources. However, it is crucial to note the environmental threats arising from the presence of Pb, Cr, Ni, and F in PG. This study investigated the effect of immobilization and transformation of four elements during co-pyrolysis with biomass and its components. The co-pyrolysis experiments were carried out in a tube furnace with a mixture of PG and corn stover (CS), cellulose (C), lignin (L), glucose (G). Co-pyrolysis occurred at varying temperatures (600 °C, 700 °C, 800 °C, and 900 °C) and different addition ratios (10%, 15%, and 20%). The results indicated that an increase in co-pyrolysis temperature was more conducive to the immobilization and transformation of harmful elements in PG, demonstrating significant efficacy in controlling F. Additionally, the addition of biomass components exerts a significant impact on inhibiting product toxicity, with small molecules such as glucose playing a prominent role in this process. The mechanism underlying the control of harmful elements during co-pyrolysis of PG and biomass was characterized by three main aspects. Firstly, biomass components have the potential to melt-encapsulate the harmful elements in PG, leading to precipitation. Secondly, the pyrolysis gas produced during the co-pyrolysis process contributes to the formation of a rich pore structure in the product. Finally, this process aids in transforming hazardous substances into less harmful forms and stabilizing these elements. The findings of this study are instrumental in optimizing the biomass and PG blend to mitigate the environmental impact of their co-pyrolysis products.

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

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

Potential of artificial soil preparation for vegetation restoration using red mud and phosphogypsum.

Red mud and phosphogypsum have long been a focus and challenge in global industrial waste management, and their low-cost and large-scale utilization technology has always been an urgent need. This study is based on the strong acid-base neutralization reaction between red mud and phosphogypsum, which contain an elemental composition similar to that of natural soil, red mud itself has characteristic of clay minerals, and other auxiliary materials (i.e. rice husk powder, bentonite, fly ash, polyacrylamide flocculant and microbial suspension) were added, so as to explore the potential of synergistically prepared artificial soil for vegetation restoration. The results showed that the artificial soils exhibited physicochemical characteristics (e.g., pH, moisture content, cation exchange capacity) similar to those of natural soil, along with abundant organic matter, nitrogen, phosphorus, and potassium contents, meeting the growth requirements of plants. The artificial soils were able to support favorable growth of suitable plants (e.g., sunflower, wheat, rye grass), accumulating high levels of diverse enzymatic activities, comparable to those in natural soils (e.g., catalase, urease, phosphatase), or even surpassing natural soils (e.g., sucrase), and rich microorganism communities, such as Cyanobacteria, Proteobacteria, Actinobacteria in the bacteria domain, and Ascomycota in the fungi domain, were initially developed. It's suggested that preparing 1 ton of artificial soil entails synergistic consumption of 613.7 kg of red mud and 244.6 kg of phosphogypsum, accounting for mass proportions of 61.4 % and 24.5 %, respectively. In future, more evaluations on the leaching loss of nutrients and alkalinity and the environmental risks of heavy metals should be conducted to more references for the artificial soil application. In summary, the preparation of artificial soil is a very simple, efficient, scalable and low-cost collaborative resource utilization scheme of red mud and phosphogypsum, which has great potential for vegetation restoration in some places such as tailings field and soil-deficient depression.

Pregelatinized hydroxypropyl distarch phosphate-reinforced calcium sulfate bone cement for bleeding bone treatment.

Considering the shortcomings of known medical hemostatic materials such as bone wax for bleeding bone management, it is essential to develop alternative bone materials capable of efficient hemostasis and bone regeneration and adaptable to clinical surgical needs. Thus, in the current work, a calcium sulfate hemihydrate and starch-based composite paste was developed and optimized. Firstly, it was found that the use of hydroxypropyl distarch phosphate (HDP) coupled with pregelatinization could generate an injectable, malleable and self-hardening paste with impressive anti-collapse ability in a dynamic aqueous environment, suggesting its potential applicability in both open and minimally invasive clinical practice. The as-hardened matrix exhibited a compressive strength of up to 61.68 ± 5.13 MPa compared to calcium sulfate cement with a compressive strength of 15.16 ± 2.42 MPa, making it a promising candidate for the temporary mechanical stabilization of bone defects. Secondly, the as-prepared paste revealed superior hemostasis and bone regenerative capabilities compared to calcium sulfate cement and bone wax, with greatly enhanced bleeding management and bone healing outcomes when subjected to testing in in vitro and in vivo models. In summary, our results confirmed that calcium sulfate bone cement reinforced with the selected starch can act as a reliable platform for bleeding bone treatment, overcoming the limitations of traditional bone hemostatic agents.

Positional accuracy of a single implant analog in additively manufactured casts in biobased model resin.

OBJECTIVES: To evaluate the positional accuracy of implant analogs in biobased model resin by comparing them to that of implant analogs in model resin casts and conventional analogs in dental stone casts. METHODS: Polyvinylsiloxane impressions of a partially edentulous mandibular model with a single implant were made and poured in type IV dental stone. The same model was also digitized with an intraoral scanner and additively manufactured implant casts were fabricated in biobased model resin (FotoDent biobased model) and model resin (FotoDent model 2 beige-opaque) (n = 8). All casts and the model were digitized with a laboratory scanner, and the scan files were imported into a 3-dimensional analysis software (Geomagic Control X). The linear deviations of 2 standardized points on the scan body used during digitization were automatically calculated on x-, y-, and z-axes. Average deviations were used to define precision, and 1-way analysis of variance and Tukey HSD tests were used for statistical analyses (α = 0.05). RESULTS: Biobased model resin led to higher deviations than dental stone (all axes, P ≤ 0.031) and model resin (y-axis, P = 0.015). Biobased model resin resulted in the lowest precision of implant analog position (P ≤ 0.049). The difference in the positional accuracy of implant analogs of model resin and stone casts was nonsignificant (P ≥ 0.196). CONCLUSIONS: Implant analogs in biobased model resin casts mostly had lower positional accuracy, whereas those in model resin and stone casts had similar positional accuracy. Regardless of the material, analogs deviated more towards mesial, while buccal deviations in additively manufactured casts and lingual deviations in stone casts were more prominent.

Application of phosphogypsum and phosphate-solubilizing fungi to Pb remediation: From simulation to in vivo incubation.

Phosphogypsum (PG) is the produced solid waste during phosphorus (P) extraction from phosphate rocks. PG is featured by its abundant PO43- and SO42-. This study investigated the utilization of PG as a material for lead (Pb) remediation, with the assistance of functional fungus. Aspergillus niger (A. niger) is a typical phosphate-solubilizing fungi (PSF), which has high ability to secret organic acids. Oxalic acid is its major secreted organic acid, which is often applied to enhance the P release from phosphate minerals. In this study, synthetic oxalic acid increased the immobilization rate of Pb2+ up to >99 % with the addition of PG. Then, it was observed that biogenic oxalic acid from A. niger can achieve comparable remediation effects. This was due to that PG could provide sufficient P for fungal growth, which allowed sustainable remediation. Subsequently, oxalic acid secreted by A. niger significantly increased the release of active P from PG, and then induced the formation of PPb minerals. In addition, other metabolites of A. niger (such as tyrosine-like substance) can also be complexed with Pb2+. Simultaneously, A. niger did not induce evidently elevation water-soluble fluorine (F) as PG contained abundant Ca2+. Moreover, this study elucidated that oversupply of PG promoted the formation of anglesite (Ksp = 1.6 × 10-8, relatively unstable), whereas the formation of lead oxalate (Ksp = 4.8 × 10-10, relatively stable) was reduced. This study hence shed a bright light on the sustainable utilization of PG for fungus-assisted remediation of heavy metals.

Origin and modern microbial ecology of secondary mineral deposits in Lehman Caves, Great Basin National Park, NV, USA.

Lehman Caves is an extensively decorated high desert cave that represents one of the main tourist attractions in Great Basin National Park, Nevada. Although traditionally considered a water table cave, recent studies identified abundant speleogenetic features consistent with a hypogenic and, potentially, sulfuric acid origin. Here, we characterized white mineral deposits in the Gypsum Annex (GA) passage to determine whether these secondary deposits represent biogenic minerals formed during sulfuric acid corrosion and explored microbial communities associated with these and other mineral deposits throughout the cave. Powder X-ray diffraction (pXRD), scanning electron microscopy with electron dispersive spectroscopy (SEM-EDS), and electron microprobe analyses (EPMA) showed that, while most white mineral deposits from the GA contain gypsum, they also contain abundant calcite, silica, and other phases. Gypsum and carbonate-associated sulfate isotopic values of these deposits are variable, with δ34SV-CDT between +9.7‰ and +26.1‰, and do not reflect depleted values typically associated with replacement gypsum formed during sulfuric acid speleogenesis. Petrographic observations show that the sulfates likely co-precipitated with carbonate and SiO2 phases. Taken together, these data suggest that the deposits resulted from later-stage meteoric events and not during an initial episode of sulfuric acid speleogenesis. Most sedimentary and mineral deposits in Lehman Caves have very low microbial biomass, with the exception of select areas along the main tour route that have been impacted by tourist traffic. High-throughput 16S rRNA gene amplicon sequencing showed that microbial communities in GA sediments are distinct from those in other parts of the cave. The microbial communities that inhabit these oligotrophic secondary mineral deposits include OTUs related to known ammonia-oxidizing Nitrosococcales and Thaumarchaeota, as well as common soil taxa such as Acidobacteriota and Proteobacteria. This study reveals microbial and mineralogical diversity in a previously understudied cave and expands our understanding of the geomicrobiology of desert hypogene cave systems.

Influences of pretreatment methods on the mechanical and environmental behaviors of PG-GGBS-LM ternary stabilizer.

Phosphogypsum is a kind of acidic industrial byproducts with high content of soluble phosphorus and fluorine pollutants, which requires to be pretreated when used as cementitious material to (partial) replace traditional Portland cement. In this study, five different pretreatment methods were proposed for comparative analysis to examine the pretreatment effect on the mechanical and environmental behaviors of ternary phosphogypsum (PG), ground granulated blast-furnace slag (GGBS), and lime (LM) mixed stabilizer. Series laboratory tests, including unconfined compressive strength (UCS), pH, phosphorus (P)/fluorine (F) leaching, scanning electron microscopy (SEM), and X-ray diffraction (XRD) tests, were conducted to comprehend the macro- and microscopic mechanism. The results show that it is essential to grind raw PG to finer powdered state, so that it reacts more easily and quickly with LM and water. In addition, it was noticed that the UCS and P/F leaching concentration are not only affected by the mixing proportion of the PG-GGBS-LM ternary stabilizer, but also by the curing duration. The UCS increases rapidly from initial curing period and then grows slowly after 28 days of curing. From the perspective of strength evolution, mixing proportion of PG: GGBS: LM = 15:80:5 is optimal, but considering the economy and environmental related issues, PG: GGBS: LM = 30:65:5 was regarded as a more attractive choice. The findings can provide a reference for the selection of pretreatment methods and design of PG-based cementitious materials suited for stabilized soils.

Preparation and property studies of ferric sulfoaluminate cement based on Bayer red mud and phosphogypsum.

The Bayer red mud (RM) and phosphogypsum (PG) accumulation have caused significant environmental contamination. However, practical and effective resource utilization technologies are still lacking currently. This work aims to develop ferric sulfoaluminate cement (FSAC) employing low-cost materials including Bayer red mud, phosphogypsum, and other materials. This method effectively improves the utilization rate of Bayer red mud and phosphogypsum. Under the premise of ensuring the performance of FSAC, the utilization rate of solid waste can reach up to 48.56%. The effects of different red mud dosages on cement mineral formation, workability, and mechanical properties are investigated. Then, untreated phosphogypsum is adopted as a retarder for FSAC, and the hydration process, working properties, mechanical properties, types of hydration products, and morphology of FSAC are explored. The results suggest that the crystal transformation of Ye'elemite C 4 A 3 S ¯  is promoted with the increase of Bayer red mud content. Cubic crystal system Ye'elemite C 4 A 3 S ¯ - c  with higher hydration activity is generated, which increases the early strength of cement but greatly reduces the setting time, hindering the later strength growth. Untreated phosphogypsum can effectively delay the early hydration process of FSAC, prolong the setting time of cement, and increase the strength of FSAC in the later stage. When the dosage of Bayer red mud and phosphogypsum is 17.64% and 9.21%, respectively, with phosphogypsum dosage of 20%, the prepared FSAC has satisfactory mechanical properties, and the 3-day and 90-day compressive strengths are 34.6 MPa and 57.1 MPa, respectively. In addition, the study of heavy metal leaching indicates that the FSAC prepared by Bayer red mud, phosphogypsum, and other raw materials will generate no environment pollution, and the solidification of heavy metal elements in the cement slurry is superior.

Plasma and interstitial fluid antibiotic levels of subcutaneously implanted compounded florfenicol calcium sulfate beads in New Zealand White rabbits (Oryctolagus cuniculus).

OBJECTIVE: To determine antibiotic levels in plasma and interstitial fluid (ISF) after SC placement of compounded florfenicol (FF) calcium sulfate beads (CSBs) in New Zealand White rabbits (Oryctolagus cuniculus). ANIMALS: 6 juvenile female rabbits (n = 5 treatment and 1 control). METHODS: An ultrafiltration probe and CSBs were placed SC in 6 rabbits (n = 5 for FF CSBs and 1 for control CSBs). Plasma (3, 6, 12, 24, and 48 hours and 7, 14, and 21 days) and ISF (daily for 21 days) samples were collected, and FF was measured by HPLC for pharmacokinetic analysis. Hematology, biochemistry, and histopathology were assessed. RESULTS: Means ± SD for the area under the curve, maximum concentration, time of maximum concentration, terminal half-life, and mean residence time to the last data point for plasma and ISF were 16.63 ± 8.16 and 17,902 ± 7,564 h·µg/mL, 0.79 ± 0.38 and 245 ± 223 µg/mL, 2.90 ± 0.3 and 59 ± 40 hours, 30.81 ± 16.9 and 27.3 ± 9.39 hours, 23.4 ± 10 and 73.7 ± 13 hours, respectively. Plasma FF was < 2 µg/mL at all time points. The ISF FF remained > 8 µg/mL for 109.98 to 231.58 hours. One rabbit death occurred during treatment, but the cause of death was undetermined. Local tissue inflammation was present, but no clinically significant systemic adverse effects were found on hematology, biochemistry, or histopathology in the remaining rabbits. CLINICAL RELEVANCE: Florfenicol CSBs maintained antibiotic concentrations in ISF at levels likely to be effective against bacteria sensitive to > 8 µg/mL for 5 to 10 days while maintaining low (< 2 µg/mL) plasma levels. Florfenicol CSBs may be effective for local antibiotic treatment in rabbit abscesses.

Synergistic effect of biochar with gypsum, lime, and farm manure on the growth and tolerance in rice plants under different salt-affected soils.

Soil salinization and sodication harm soil fertility and crop production, especially in dry regions. To combat this, using biochar combined with gypsum, lime, and farm manure is a promising solution for improving salt-affected soils. In a pot experiment, cotton stick biochar (BC) was applied at a rate of 20 t/ha in combination with gypsum (G), lime (L), and farm manure (F) at rates of 5 and 10 t/ha. These were denoted as BCG-5, BCL-5, BCF-5, BCG-10, BCL-10, and BCF-10. Three different types of soils with electrical conductivity (EC) to sodium adsorption ratio (SAR) ratios of 2.45:13.7, 9.45:22, and 11.56:40 were used for experimentation. The application of BCG-10 led to significant improvements in rice biomass, chlorophyll content, and overall growth. It was observed that applying BCG-10 to soils increased the membrane stability index by 75% in EC:SAR (2.45:13.7), 97% in EC:SAR (9.45:22), and 40% in EC:SAR (11.56:40) compared to respective control treatments. After BCG-10 was applied, the hydrogen peroxide in leaves dropped by 29%, 23%, and 21% in EC:SAR (2.45:13.7), EC:SAR (9.45:22), and EC:SAR (11.56:40) soils, relative to their controls, respectively. The application of BCG-10 resulted in glycine betaine increases of 60, 119, and 165% in EC: SAR (2.45:13.7), EC: SAR (9.45:22), and EC: SAR (11.56:40) soils. EC: SAR (2.45:13.7), EC: SAR (9.45:22), and EC: SAR (11.56:40) soils all had 70, 109, and 130% more ascorbic acid in BCG-10 applied treatment, respectively. The results of this experiment show that BCG-10 increased the growth and physiological traits of rice plants were exposed to different levels of salt stress. This was achieved by lowering hydrogen peroxide levels, making plant cells more stable, and increasing non-enzymatic activity.

Amelioration of the physicochemical properties enhanced the resilience of bacteria in bauxite residues.

Bacteria-driven strategies have gained attention because of their effectiveness, viability, and cost-efficiency in the soil formation process of bauxite residues. However, further investigation is needed to enhance the extreme environment of bauxite residues and facilitate long-term sustainable development of bacteria. Here, soil, phosphogypsum, and leaf litter were selected as amendments, and soil and leaf litter were also used as bacterial inoculants in a 12-month microcosm experiment with bauxite residues. The results showed significant improvements in physicochemical properties, including alkalinity, organic carbon content, nutrient availability, and physical structure, when bauxite residue was mixed with amendments, particularly when different amendments were combined. The diversity, structure, and function of the bacterial community were significantly enhanced with the amelioration of the physicochemical properties. In the treated samples, especially those treated with a combination of different amendments, the relative abundance (RA) of alkali-resistant bacterial taxa decreased, whereas the RA of some common taxa found in normal soil increased, and the structure of the bacterial community gradually changed towards that of normal soil. A strong correlation between physicochemical and biological properties was found. These findings suggest that rational application of soil, phosphogypsum, and leaf litter effectively improves the environmental conditions of bauxite residues and facilitate long-term sustainable bacterial communities.

Time to full weight-bearing with the use of a calcium sulfate-calcium phosphate bone substitute as a bone void filler following extended curettage in the treatment of primary benign bone tumours.

PURPOSE: The primary objective of this study was to determine time to full weight-bearing after the use of a calcium-sulfate-calcium phosphate bone substitute (CaSO4/CaPO4) as a bone void filler in the treatment of primary benign bone tumours following intralesional curettage. The secondary objectives were to determine surgical complications and recurrence rates. METHODS: Retrospective review of patients identified from a surgeon-specific orthopaedic oncology database, who underwent curettage of benign bone tumours and subsequent bone void filling with CaSO4/CaPO4. RESULTS: A total of 39 patients (20 males, 19 females) met inclusion criteria with an average age of 31 years (range: 13 to 62 years), a median follow-up of 3.7 years, and a maximum follow-up of 11 years. The most common tumour diagnosis was giant cell tumour of bone (GCT) (n = 19), and the most common location was the proximal tibia (n = 9). The mean volume of tumour excised was 74.1 cm3 including extraosseous bone expansion due to tumour growth, with a mean of volume of 21.4 mL of CaSO4/CaPO4 used to fill the intraosseous cavitary defects to restore normal bone anatomy. None of the lesions required additional internal fixation. The primary outcome measure, average time to full weight-bearing/full range of motion, was 11 weeks and 6 weeks for upper and lower extremity lesions, respectively. Secondary outcomes included tumour recurrence requiring reoperation in five patients and infection requiring reoperation in two patients. CONCLUSION: This study demonstrates that CaSO4/CaPO4 is a viable option as a bone void filler in the reconstruction of cavitary defects following removal of primary benign bone tumours. CaSO4/CaPO4 provides sufficient bone regeneration early in the post-operative period to allow progression to full weight-bearing within weeks without the need for internal fixation. There were no graft-specific complications noted.

Study on triaxial compression performance and damage characteristics of fiber-reinforced ecological matrix cementing gangue gypsum fill material.

Polypropylene fiber was equally mixed into alkali-activated slag fly ash geopolymer in order to ensure the filling effect of mine goaf and improve the stability of cemented gangue paste filling material with ecological matrix. Triaxial compression tests were then conducted under various conditions. The mechanical properties and damage characteristics of composite paste filling materials are studied, and the damage evolution model of paste filling materials under triaxial compression is established, based on the deviatoric stress-strain curve generated by the progressive failure behavior of samples. Internal physical and chemical mechanisms of the evolution of structure and characteristics are elucidated and comprehended via the use of SEM-EDS and XRD micro-techniques. The results show that the fiber can effectively improve the ultimate strength and the corresponding effective stress strength index of the sample within the scope of the experimental study. The best strengthening effect is achieved when the amount of NaOH is 3% of the mass of the solid material, the amount of fiber is 5‰ of the mass of the solid material, and the length of the fiber is about 12 mm. The action mode of the fiber in the sample is mainly divided into single-grip anchoring and three-dimensional mesh traction. As the crack initiates and develops, connection occurs in the matrix, where the fiber has an obvious interference and retardation effect on the crack propagation, thereby transforming the brittle failure into a ductile failure and consequently improving the fracture properties of the ecological cementitious coal gangue matrix. The theoretical damage evolution model of a segmented filling body is constructed by taking the initial compaction stage end point as the critical point, and the curve of the damage evolution model of the specimen under different conditions is obtained. The theoretical model is verified by the results from the triaxial compression test. We concluded that the experimental curve is in good agreement with the theoretical curve. Therefore, the established theoretical model has a certain reference value for the analysis and evaluation of the mechanical properties of paste filling materials. The research results can improve the utilization rate of solid waste resources.

Antibiotic calcium sulphate beads lower the bacterial burden and prevent infection in a mouse model of periprosthetic joint infection.

Aims: Delayed postoperative inoculation of orthopaedic implants with persistent wound drainage or bacterial seeding of a haematoma can result in periprosthetic joint infection (PJI). The aim of this in vivo study was to compare the efficacy of vancomycin powder with vancomycin-eluting calcium sulphate beads in preventing PJI due to delayed inoculation. Methods: A mouse model of PJI of the knee was used. Mice were randomized into groups with intervention at the time of surgery (postoperative day (POD) 0): a sterile control (SC; n = 6); infected control (IC; n = 15); systemic vancomycin (SV; n = 9); vancomycin powder (VP; n = 21); and vancomycin bead (VB; n = 19) groups. Delayed inoculation was introduced during an arthrotomy on POD 7 with 1 × 105 colony-forming units (CFUs) of a bioluminescent strain of Staphylococcus aureus. The bacterial burden was monitored using bioluminescence in vivo. All mice were killed on POD 21. Implants and soft-tissue were harvested and sonicated for analysis of the CFUs. Results: The mean in vivo bioluminescence in the VB group was significantly lower on POD 8 and POD 10 compared with the other groups. There was a significant 1.3-log10 (95%) and 1.5-log10 (97%) reduction in mean soft-tissue CFUs in the VB group compared with the VP and IC groups (3.6 × 103 vs 7.0 × 104; p = 0.022; 3.6 × 103 vs 1.0 × 105; p = 0.007, respectively) at POD 21. There was a significant 1.6-log10 (98%) reduction in mean implant CFUs in the VB group compared with the IC group (1.3 × 100 vs 4.7 × 101, respectively; p = 0.038). Combined soft-tissue and implant infection was prevented in 10 of 19 mice (53%) in the VB group as opposed to 5 of 21 (24%) in the VP group, 3 of 15 (20%) in the IC group, and 0% in the SV group. Conclusion: In our in vivo mouse model, antibiotic-releasing calcium sulphate beads appeared to outperform vancomycin powder alone in lowering the bacterial burden and preventing soft-tissue and implant infections.

Near-Infrared Triggered Biodegradable Microneedle Patch for Controlled Macromolecule Drug Release.

Transdermal drug delivery of macromolecule drugs attracts significant attention due to the advantage of convenience and biocompatibility. However, the practical usage of it is limited by the low delivery efficiency and poor drug absorption. To develop an efficient, safe, and controllable transdermal delivery method, the near-infrared (NIR) triggered calcium sulfate and gelatin biodegradable composite microneedle (MN) patches are developed. The MN patches are fabricated by polydimethylsiloxane (PDMS) molds, and the structure data can be adjusted by changing the molds. Such an MN patch can release both macro and micro molecule drugs. After loading with photothermal converter IR780, which can transfer energy of light to heat, the release of macromolecule drugs in MNs can be controlled by applying NIR irradiation. The control effect can be enhanced by spraying 1-tetradecanol (TD) coating and optimizing the ratio (weight) of gelatin and calcium sulfate to 2:6. Besides, the MN patch can deliver drugs through the skin barrier, and the process can be controlled by NIR. Moreover, the insulin-loaded MN patch exhibits some therapeutic effects on healthy mice. This work suggests that biodegradable MNs can achieve controllable drug delivery and potentially be applied in individual treatment via transdermal ingestion.

Facet-engineering strategy of phosphogypsum for production of mineral slow-release fertilizers with efficient nutrient fixation and delivery.

Phosphogypsum (PG) presents considerable potential for agricultural applications as a secondary primary resource. However, it currently lacks environmentally friendly, economically viable, efficient, and sustainable reuse protocols. This study firstly developed a PG-based mineral slow-release fertilizer (MSRFs) by internalization and fixation of urea within the PG lattice via facet-engineering strategy. The molecular dynamics simulations demonstrated that the binding energy of urea to the (041) facet of PG surpassed that of the (021) and (020) facets, with urea's desorption energy on the (041) facet notably higher than on the (021) and (020) facets. Guided by these calculations, we selectively exposed the (041) dominant facet of PG, and then achieving complete urea fixation within the PG lattice to form urea-PG (UPG). UPG exhibited a remarkable 48-fold extension in N release longevity in solution and a 45.77% increase in N use efficiency by plants compared to conventional urea. The facet-engineering of PG enhances the internalization and fixation efficiency of urea for slow N delivery, thereby promoting nutrient uptake for plant growth. Furthermore, we elucidated the intricate interplay between urea and PG at the molecular level, revealing the involvement of hydrogen and ionic bonding. This specific bonding structure imparts exceptional thermal stability and water resistance to the urea within UPG under environmental conditions. This study has the potential to provide insights into the high-value utilization of PG and present innovative ideas for designing efficient MSRFs.

Elemental sulfur biorecovery from phosphogypsum using oxygen-membrane biofilm reactor: Bioreactor parameters optimization, metagenomic analysis and metabolic prediction of the biofilm activity.

This work investigated elemental sulfur (S0) biorecovery from Phosphogypsum (PG) using sulfur-oxidizing bacteria in an O2-based membrane biofilm reactor (MBfR). The system was first optimized using synthetic sulfide medium (SSM) as influent, then switched to biogenic sulfide medium (BSM) generated by biological reduction of PG alkaline leachate. The results using SSM had high sulfide-oxidation efficiency (98 %), sulfide to S0 conversion (∼90 %), and S0 production rate up to 2.7 g S0/(m2.d), when the O2/S ratio was ∼0.5 g O2/g S. With the BSM influent, the system maintained high sulfide-to-S0 conversion rate (97 %), and S0-production rate of 1.6 g S0/(m2.d). Metagenomic analysis revealed that Thauera was the dominant genus in SSM and BSM biofilms. Furthermore, influent composition affected the bacterial community structure and abundances of functional microbial sulfur genes, modifying the sulfur-transformation pathways in the biofilms. Overall, this work shows promise for O2-MBfR usage in S0 biorecovery from PG-leachate and other sulfidogenic effluents.