Bioleaching exhibits high potential for the processing of low-grade complex mineral resources. With the development of the economy and an increase in demand, rare earth elements (REEs) in secondary ...resources, such as phosphogypsum, red mud and coal-related resources, are gaining more and more attention. In this review, the bioleaching performance of diverse microorganisms is summarized and compared for primary (mainly monazite) and secondary REE resources, based on publications from the past decade. The mineral characteristics of these REE resources are different, as they can be found in phosphate, sulfate, or silicate forms. Correspondingly, microbial species suitable for use in bioleaching differ. The most efficient bioleaching microbe for monazite is Paecilomyces sp., while Acidianus manzaensis is effective in processing red mud. Acidophilic sulfur oxidizers are suitable for processing acidic phosphogypsum. Acidithiobacillus thiooxidans could recover a significant amount of REEs from coal fly ash. In particular, monazite has a high REE content but extremely low bioleaching efficiency compared to that of secondary resources, supporting the understanding that bioleaching approaches are more competitive for minerals with low REE contents. Overall, great progress has been made over the last decade, as considerable REE recovery rates have been achieved, and the main metabolites of microbes were identified. However, numerous challenges still exist. Future efforts should focus on improving biorecovery efficiency, reducing the cost of cell-culture media, and exploring the interaction mechanism between cells and minerals, with an emphasis on mineralogical phase transformations and the molecular regulation mechanisms inside cells during the bioleaching process.
It is well known that stem cells reside within tissue engineering functional microenvironments that physically localize them and direct their stem cell fate. Recent efforts in the development of more ...complex and engineered scaffold technologies, together with new understanding of stem cell behavior in vitro, have provided a new impetus to study regulation and directing stem cell fate. A variety of tissue engineering technologies have been developed to regulate the fate of stem cells. Traditional methods to change the fate of stem cells are adding growth factors or some signaling pathways. In recent years, many studies have revealed that the geometrical microenvironment played an essential role in regulating the fate of stem cells, and the physical factors of scaffolds including mechanical properties, pore sizes, porosity, surface stiffness, three-dimensional structures, and mechanical stimulation may affect the fate of stem cells. Chemical factors such as cell-adhesive ligands and exogenous growth factors would also regulate the fate of stem cells. Understanding how these physical and chemical cues affect the fate of stem cells is essential for building more complex and controlled scaffolds for directing stem cell fate.
Jaw bone repair requires scaffold with bone regeneration, antibacterial function and personalized size. This study proposed 3D printed degradable calcium phosphate scaffolds with antibacterial ...functions for regeneration of jaw bone. Calcium phosphate powders and berberine were combined to modulate the printing inks. Porous scaffolds were fabricated by direct extrusion 3D printing and cross-linked with sodium alginate in situ. The dimensional size, shape and porosity of scaffolds were precisely customized by 3D printing. Berberine-loaded scaffolds show sustained release of antimicrobial drugs. By adjusting the concentration and cross-linking time of calcium chloride, the cross-linking degree of the scaffold can be adjusted and the drug load of the scaffold can be controlled. The young's modulus of 3DP scaffold was about 1.3 MPa. After freeze-drying, the shrinkage was about 24.4% and less swelling was observed, indicating that the scaffold had sufficient structural stability. In vitro biological test showed that the 3DP scaffold had low cytotoxicity and it was beneficial to MC3T3 cell adhesion and proliferation. 3D printed calcium phosphate scaffolds with controlled-release antibacterial properties is a promising biomaterials for jaw repair.
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•Calcium phosphate powders and berberine were combined to modulate the printing inks.•Porous scaffolds were fabricated by direct extrusion 3D printing.•Porous scaffolds were cross-linked with sodium alginate in situ.•The dimensional size, shape and porosity of scaffolds were precisely customized by 3D printing.•Berberine-loaded scaffolds show sustained release of antimicrobial drugs.
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•Abstract Hydroxyapatite coating was constructed by a modified hydrothermal approach, which employing chelated calcium to enhance the medium stability and increase the generated ...amount.•The 3D printed integrative hydroxyapatite/titanium intervertebral cages contribute to osteogenic differentiation of BMSCs according to qRT-PCR and Transcriptome results.•The integrative titanium/hydroxyapatite intervertebral cage design, compared with typical split cage/graft cage, showed better bone tissue ingrowth and spinal fusion ability.
3D printed porous titanium cage is believed with physiology mechanical properties and biocompatibility for orthopedic usage. Typical split cage design with a grafting window and infilled bone graft has raised a lot of questions. In this research, a modified hydrothermal approach, employing chelated calcium to enhance the medium stability and increase the generated amount, is proposed to construct bioactive hydroxyapatite coating inside the porous structure of 3D printed porous titanium cage. The in vitro and transcriptomic results indicated the hydroxyapatite enhanced the cells physical sensing system, therefore enhanced the osteogenesis inside titanium/hydroxyapatite cage. The in vivo goat spinal fusion experiment indicated the integrative titanium/hydroxyapatite cage, compared with typical split cage/graft cage, showed better bone tissue ingrowth and spinal fusion ability. This research provides a promising hydroxyapatite coating strategy for complex porous structure and revealed the potential advantage of integrative titanium/hydroxyapatite intervertebral cage design.
Purpose
The purpose of this paper is to quantitatively measure the vulnerability level of the whole rural social-ecological system in Yunnan Province and to analyze the spatial differences of the ...vulnerability in different regions.
Design/methodology/approach
Based on the “exposure-sensitivity-adaptability” vulnerability assessment framework, this paper establishes the index system of rural social-ecological system vulnerability to climate change. Combined with the questionnaire survey and meteorological data, the entropy method was used to measure and analyze the vulnerability level and influencing factors of the overall rural social-ecological system in Yunnan Province. At the same time, the vulnerability level of social-ecological system in Yunnan Province is divided into five levels, and the spatial differences of vulnerability level of 16 states (cities) in Yunnan Province are analyzed.
Findings
The results show that: the social-ecological system has high exposure to climate change (0.809), strong sensitivity (0.729), moderate adaptability (0.297) and overall system vulnerability is at a medium level (0.373). Yunnan Province is divided into five levels of social-ecological system vulnerable areas. The areas of extreme, severe, moderate, mild and slight vulnerability account for 21.45%, 24.65%, 36.82%, 13.18% and 3.90% of the whole province, respectively. The geographical division and vulnerability division of Yunnan Province are basically consistent in space.
Originality/value
Comprehensive evaluation of the vulnerability of the social-ecological system of Yunnan Province to climate change is the scientific basis for the country to formulate countermeasures against climate change, and it is also the need to improve the adaptability of the social and economic system of the fragile area, reduce the vulnerability and realize the sustainable development of national social economy. The research results can provide a basis for decision-making of climate adaptation in Yunnan and other regions and provide methods and indicators for the assessment of social-ecological system vulnerability under the background of climate change.
Hepatocellular carcinoma (HCC) is one of the most deadly tumors. Transarterial chemoembolization (TACE) is effective for unresectable HCC. In recent years, miRNAs have been proposed as novel ...diagnostic and prognostic tools for HCC. This study aimed to identify whether microRNAs (miRNAs) can serve as biomarkers to reliably predict outcome before HCC patients are treated with TACE.
Eleven miRNAs (miR-, miR-19a, miR-101-3p, miR-199a-5p, miR-200a, miR-21, miR-214, miR-221, miR-222, miR-223 and miR-, -5p) were quantified by quantitative real-time PCR (qRT-PCR) in 136 HCC patients' serum before they received TACE therapy. Univariate and multivariate analysis were used to identify the prognostic value of clinical parameters and miRNAs. Area under the receiver operating characteristic curve (AUC) was used to evaluate the prediction potency.
The levels of some miRNAs were dramatically associated with clinicopathologic features regarding Child-Puge class, AFP, tumor size and satellite nodules. Univariate analysis revealed that miR-200a, miR-21, miR-122 and miR-224-5p were significantly associated with patients' survival. Multivariate analysis demonstrated that AFP, satellite nodules and miR-200a were the independent prognostic factors associated with survival in this cohort (p = 0.000, 0.001, 0.000, respectively). The probability of the prognostic accuracy of miR-200a was 81.64% (74.47% specificity and 88.76% sensitivity), which was higher than the classifier established by combination of AFP and satellite nodules (76.87% probability, 70.21% specificity and 69.66% sensitivity). Furthermore, the combination of AFP, satellite nodules and miR-200a demonstrated as a classifier for HCC prognosis, yielding a ROC curve area of 88.19% (93.62% specificity and 68.54% sensitivity).
Our study indicated that serum miR-200a may prognosticate disease outcome in HCC patients with TACE therapy. Therefore, miR-200a can potentially guide individualized treatment for HCC patients with a high risk of TACE treatment failures.
Enhanced osteogenesis and angiogenesis capacity of 3D printed porous PLGA/n-HA scaffolds incorporated with magnesium phosphate.
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•Porous PLGA/n-HA/MgP composite (PHM) scaffolds are ...fabricated by FDM.•Doping of MgP accelerates the degradation of scaffolds and buffers the acid environment caused by PLGA degradation.•Scaffold with 10% MgP ratio shows good effect on osteogenesis and neovascularization.•Over 30% MgP content shows a negative effect on bone regeneration.
The osteogenic and angiogenic characteristics are crucial for the selection of bone substitute materials and structural design. This study proposed a porous PLGA/n-HA/MgP composited scaffold by printing of the poly (lactide-coglycolide) (PLGA), nano-hydroxyapatite (n-HA), and magnesium phosphate (MgP). The physicochemical properties, osteogenic activities, and pro-angiogenic impacts of porous 3D printed PLGA/n-HA scaffolds with variable MgP concentration were investigated. The results indicated that the presence of MgP in the composite promoted scaffold degradation and buffered the acidic environment induced by PLGA degradation. The highest pro-osteogenic activity has been observed in PLGA/n-HA/10% MgP (PH10M) group, which up-regulated BMP2 and RUNX2 factors in vitro and in vivo. Nevertheless, at a maximal ion release of 7.2 mmol/L, PLGA/n-HA/30% MgP (PH30M) marginally reduced theosteogenic differentiation of osteoblasts through the RANKL/OPG pathway. In vitro, PLGA/n-HA/20% MgP (PH20M) demonstrated superior migration, pro-angiogenic factor expression, and angiogenesis compared to other groups, and the histological investigation corroborated the improved angiogenesis in PH10M and PH20M. In conclusion, suitable MgP ratio shows the potential to improve the osteogenic and angiogenic properties of PLGA/n-HA-based composites in orthopedic applications.
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•A heterogeneous structure was built via a Voronoi-Thiessen based parametric modeling method.•Heterogeneity had little influence on porosity, thus, mechanical/hydrodynamic ...properties.•Irregular local geometry mimicked cancellous bone structure and promoted cellular behavior.•50% heterogeneity (SR structure) kept a balance of structure integrity and osteogenesis.
In nature, many natural porous tissues of animals or plants follow heterogeneous structures pattern. Including turtle back pattern, leaf veins, wood porous fiber and porous cancellous bone are classic heterogeneous structures. In order to better design bionic microenvironment porous bone implants, herein, a bionic porous structure based on Voronoi-Thiessen diagram to create heterogeneous topology microenvironment promoting bone regeneration were proposed. Porous structures with tunable heterogeneity were built and achieved by selective laser melting (SLM). The topology analysis revealed the introduce of heterogeneity brought wide pore size distribution and irregular topology. The mechanical and hydrodynamics properties were predesigned and simulated by finite element analysis (FEA). The heterogeneity hardly influenced the overall strength, stiffness and permeability but the irregular stress and fluid shear rate distribution in FEA results indicated fluctuating local stiffness and permeability. In vitro and in vivo experimental results indicated that Quasi-homogeneous structure had irregular topology mimicking that of the natural bone structure and semi-heterogenous structure shown better osteogenesis. It is found that the scaffold heterogeneous microenvironment factors play important roles for bone regeneration, and which is crucial for the development of new orthopedic implants.
Introduction of metals as biomaterials has been known for a long time. In the early development, sufficient strength and suitable mechanical properties were the main considerations for metal ...implants. With the development of new generations of biomaterials, the concepts of bioactive and biodegradable materials were proposed. Biological function design is very import for metal implants in biomedical applications. Three crucial design criteria are summarized for developing metal implants: (1) mechanical properties that mimic the host tissues; (2) sufficient bioactivities to form bio-bonding between implants and surrounding tissues; and (3) a degradation rate that matches tissue regeneration and biodegradability. This article reviews the development of metal implants and their applications in biomedical engineering. Development trends and future perspectives of metallic biomaterials are also discussed.
Repair of critical bone defects is a challenge in the orthopedic clinic. 3D printing is an advanced personalized manufacturing technology that can accurately shape internal structures and external ...contours. In this study, the composite scaffolds of polylactic acid (PLA) and nano-hydroxyapatite (n-HA) were manufactured by the fused deposition modeling (FDM) technique. Equal mass PLA and n-HA were uniformly mixed to simulate the organic and inorganic phases of natural bone. The suitability of the composite scaffolds was evaluated by material characterization, mechanical property, and
biocompatibility, and the osteogenesis induction
was further tested. Finally, the printed scaffold was implanted into the rabbit femoral defect model to evaluate the osteogenic ability
. The results showed that the composite scaffold had sufficient mechanical strength, appropriate pore size, and biocompatibility. Most importantly, the osteogenic induction performance of the composite scaffold was significantly better than that of the pure PLA scaffold. In conclusion, the PLA/n-HA scaffold is a promising composite biomaterial for bone defect repair and has excellent clinical transformation potential.
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