Plastination Research Articles

Expression and Localization of Thrombospondins, Plastin 3, and STIM1 in Different Cartilage Compartments of the Osteoarthritic Varus Knee.

Osteoarthritis (OA) is a multifactorial disease which is characterized by a change in the homeostasis of the extracellular matrix (ECM). The ECM is essential for the function of the articular cartilage and plays an important role in cartilage mechanotransduction. To provide a better understanding of the interaction between the ECM and the actin cytoskeleton, we investigated the localization and expression of the Ca2+-dependent proteins cartilage oligomeric matrix protein (COMP), thrombospondin-1 (TSP-1), plastin 3 (PLS3) and stromal interaction molecule 1 (STIM1). We investigated 16 patients who suffered from varus knee OA and performed a topographical analysis of the cartilage from the medial and lateral compartment of the proximal tibial plateau. In a varus knee, OA is more pronounced in the medial compared to the lateral compartment as a result of an overloading due to the malalignment. We detected a location-dependent staining of PLS3 and STIM1 in the articular cartilage tissue. The staining intensity for both proteins correlated with the degree of cartilage degeneration. The staining intensity of TSP-1 was clearly reduced in the cartilage of the more affected medial compartment, an observation that was confirmed in cartilage extracts by immunoblotting. The total amount of COMP was unchanged; however, slight changes were detected in the localization of the protein. Our results provide novel information on alterations in OA cartilage suggesting that Ca2+-dependent mechanotransduction between the ECM and the actin cytoskeleton might play an essential role in the pathomechanism of OA.

Bending fatigue behavior in an advanced SiC/SiC ceramic matrix composite component at elevated temperature in air

The present study aims to understand the high-temperature bending fatigue behavior at the stress-concentrated Y-shape junction of a component made of Tyranno SA3 fiber/BN interphase/SiC matrix composite. The SiC/SiC CMC component was processed via a hybrid technique by combining Chemical Vapor Infiltration (CVI) and Polymer Impregnation and Pyrolysis (PIP) processes. Two different types of tests, namely, point-load-bending-static-test and point-load-bending-fatigue-test, were performed at 1100 °C. The point-load-bending-static test revealed quasi-ductile or shear failure owing to the lower elastic modulus of the PIP-SiC matrix. The first matrix-cracking occurred when the high-stress region reached approximately 180 MPa, which was facilitated by the pores and cracks that remained after the PIP process around the intricate Y-shape junction of the sample. The point-load-bending-fatigue tests were performed under the maximum of the fatigue stresses ranging from 180 to 290 MPa. When the maximum of the fatigue stress was lower than 60% of the static strength, multiple matrix-cracking were pronounced such that the component did not fail and withstand 1000 fatigue cycles. At higher stresses of 250 and 290 MPa, delamination due to shear stress generation at the fiber tows interface and degradation of the BN interphase ultimately led to the fracture of the component at low fatigue cycles of less than 100. Moreover, the fracture morphology of the 290-MPa-fatigue sample showed brittle failure, which was due to matrix-crack-assisted oxygen embrittlement. In addition, a brief comparison between the point-load-bending-fatigue test and the conventional tension-compression fatigue test was discussed.

Influences of the dip-coated BN interface on mechanical behavior of PIP-SiC/SiC minicomposites

SiC/SiC minicomposites with BN interfaces were fabricated by a two-step route comprising dip-coating and polymer impregnation and pyrolysis (PIP). The thickness of the dip-coated BN interface was in the range of 76–300 nm, which was adjusted by dipping times. The influences of BN interface thickness on the mechanical behavior of the as-fabricated SiC/SiC minicomposites were investigated. The mechanical properties of SiC/SiC composites were improved by introducing BN interfaces, which showed an optimized tensile strength distribution with a higher Weibull modulus m. The optimal mechanical properties could be obtained in SiC/BN/SiC-2 samples with the BN interface thickness of ~160 nm. The variation trend of tensile strengths caused by the increasing interface thickness was analyzed using a probabilistic-statistical model. Especially, both the interface delamination caused by the secondary crack and the fiber Weibull parameter mfiber influenced by the BN interface coating were considered in the probabilistic-statistical model, leading to a better matching between the experimental results and the model simulation. Microstructure characterization combined with numerical analysis showed that the dip-coated BN interface with appropriate thickness played an important role in improving the mechanical properties of SiC/SiC minicomposites. The results indicated that both the ability of crack deflection of interfaces and the fiber in-situ strengths should be considered in the interface design of SiC/SiC composites.

Possibility of dopant morphology control in the process of polymer impregnation with pharmaceuticals in a supercritical CO2 medium

In this paper we present the results of polymethylmethacrylate (PMMA) impregnation with carbamazepine (CBZ) in a supercritical carbon dioxide (scCO2) medium at two different temperatures (75 °C and 105 °C) at a constant CO2 density. The obtained impregnated PMMA samples were analyzed by PXRD and Raman spectroscopy techniques. We have found that, irrespective of the impregnation process temperature, CBZ entrapped in the polymer matrix does not crystallize there but a CBZ solution in the PMMA is formed instead. It has been found that the CBZ concentration in the PMMA matrix grows as the impregnation process temperature rises due to the increase in the CBZ equilibrium concentration in the scCO2 phase, at that the conformational state of the CBZ molecules in the PMMA matrix was also found to depend on the impregnation process temperature. Finally, we showed that depending on the impregnation process temperature it is possible to obtain a PMMA matrix with either an opened or a sealed porous structure. In the latter case, not only CBZ, but also CO2 can be entrapped, remaining in the PMMA matrix in the high-density fluid state.

Transparent wood prepared by polymer impregnation of rubber wood (Hevea brasiliensis Muell. Arg)

Transparent wood (TW), a new type of composite material with good optical transmittance and excellent mechanical properties, has attracted great interest in recent years. In this study, a hydrogen peroxide strategy was used on rubber wood (Hevea brasiliensis Muell. Arg) to eliminate lignin and hemicellulose. Subsequently, delignified wood was combined with each of three impregnants of refractive index similar to that of cellulose to obtain transparent wood (TW). Impregnation with polyvinyl-pyrrolidone (PVP), polyvinyl alcohol (PVOH), and methyl methacrylate (MMA)) resulted in transparent woods, which were named PVP-DRW, PVOH-DRW, and PMMA-DRW, respectively. The micromorphologies, chemical compositions, thermal stabilities, chemical functional groups, optical transmittance, and mechanical properties of the raw RW and of each processed sample were characterized. The results showed that the optical transmittance of PVOH-DRW (76.6%, λ = 600 nm, d=0.70 mm) was similar to that of PVP-DRW (73.4%, λ = 600 nm, d = 0.74 mm) and higher than that of PMMA-DRW (64.6%, λ = 600 nm, d = 0.73 mm), but PMMA-DRW had a higher mechanical strength (fracture strength of 230.14 MPa). Therefore, the preparation of transparent wood with RW as the substrate is expected to be a potential material candidate for high-strength composites.

Complex geometry macroporous SiC ceramics obtained by 3D-printing, polymer impregnation and pyrolysis (PIP) and chemical vapor deposition (CVD)

We present here an original route for the manufacturing of SiC ceramics based on 3D printing, polymer impregnation and pyrolysis and chemical vapor deposition (CVD). The green porous elastomer structures were first prepared by fused deposition modeling (FDM) 3D-printing with a composite polyvinyl alcohol/elastomer wire and soaking in water, then impregnated with an allylhydridopolycarbosilane preceramic polymer. After crosslinking and pyrolysis, the polymer-derived ceramics were reinforced by CVD of SiC using CH3SiCl3/H2 as precursor. The multiscale structure of the SiC porous specimens was examined by X-ray tomography and scanning electron microscopy analyses. Their oxidation resistance was also studied. The pure and dense CVD-SiC coating considerably improves the oxidation resistance.

Improved thermal stability of SiCf/SiC ceramic matrix composites fabricated by PIP process

Improvement of the thermal stability of continuous SiC fiber reinforced SiC ceramic matrix composites (SiCf/SiC CMC) by the pre-treatment of SiC fillers and the suppression of oxidation during polymer impregnation and pyrolysis (PIP) process were investigated. Dense SiCf/SiC CMCs were fabricated using the slurry infiltration and PIP process under a purified argon atmosphere. Structure and mechanical properties of the SiCf/SiC CMC heated at different temperatures were evaluated. The flexural strength of the SiCf/SiC CMC decreased only 15.3%after heating at 1400 ?C, which exhibited a clear improvement compared with the literature data (49.5% loss), where severe thermal deterioration of SiCf/SiC composite occurred at high temperatures by the crystallization and decomposition of the precursor-derived ceramic matrix. The thermal stability of the SiCf/SiC CMC fabricated by PIP process was improved by the pre-treatment of SiC fillers for removing oxides and the strict atmosphere control to prevent oxidation.

Impregnation of Polymer Materials in Supercritical Media (a Review)

The review considers the advances in the field of impregnation of polymers in supercritical media over the recent years. In particular, new approaches to the process of impregnation of polymers are described, and the possibility of application of new sub- and supercritical media for these purposes is demonstrated. Specific examples and conditions of these processes are presented, and new fields of application of the method are discussed.

Early-Onset Osteoporosis: Rare Monogenic Forms Elucidate the Complexity of Disease Pathogenesis Beyond Type I Collagen.

ABSTRACTEarly‐onset osteoporosis (EOOP), characterized by low bone mineral density (BMD) and fractures, affects children, premenopausal women and men aged <50 years. EOOP may be secondary to a chronic illness, long‐term medication, nutritional deficiencies, etc. If no such cause is identified, EOOP is regarded primary and may then be related to rare variants in genes playing a pivotal role in bone homeostasis. If the cause remains unknown, EOOP is considered idiopathic. The scope of this review is to guide through clinical and genetic diagnostics of EOOP, summarize the present knowledge on rare monogenic forms of EOOP, and describe how analysis of bone biopsy samples can lead to a better understanding of the disease pathogenesis. The diagnostic pathway of EOOP is often complicated and extensive assessments may be needed to reliably exclude secondary causes. Due to the genetic heterogeneity and overlapping features in the various genetic forms of EOOP and other bone fragility disorders, the genetic diagnosis usually requires the use of next‐generation sequencing to investigate several genes simultaneously. Recent discoveries have elucidated the complexity of disease pathogenesis both regarding genetic architecture and bone tissue‐level pathology. Two rare monogenic forms of EOOP are due to defects in genes partaking in the canonical WNT pathway: LRP5 and WNT1. Variants in the genes encoding plastin‐3 (PLS3) and sphingomyelin synthase 2 (SGMS2) have also been found in children and young adults with skeletal fragility. The molecular mechanisms leading from gene defects to clinical manifestations are often not fully understood. Detailed analysis of patient‐derived transiliac bone biopsies gives valuable information to understand disease pathogenesis, distinguishes EOOP from other bone fragility disorders, and guides in patient management, but is not widely available in clinical settings. Despite the great advances in this field, EOOP remains an insufficiently explored entity and further research is needed to optimize diagnostic and therapeutic approaches. © 2022 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

An in situ Raman spectroscopic method for quantification of polyethylene glycol (PEG) in waterlogged archaeological wood

AbstractThe weakened microstructure of archaeological wood (AW) objects from waterlogged environments necessitates consolidation to avoid anisotropic shrinkage upon drying. Polymer impregnation through submergence or spraying treatments is commonly applied, and for larger and thicker objects, the impregnation period can stretch over decades. Thus, for efficient treatment, continuous monitoring of the impregnation status is required. Today, such monitoring is often destructive and expensive, requiring segments for extraction and chromatographic quantification. This study proposes an in situ Raman spectroscopic method for quantification of polyethylene glycol (PEG) in waterlogged AW. A calibration model was built on standards of PEG, cellulose powder, and milled wood lignin using orthogonal partial least squares (OPLS). The OPLS model had a strong linear relationship, and the PEG content in wood of varying degrees of degradation could be determined. However, the accuracy of the model was low with a root mean square error of prediction of 11 wt%. The low accuracy was traced to the heterogeneity in the calibration and validation set samples with regard to the small probing volume of the confocal instrumental setup.

Plasma plastin-3: A tumor marker in patients with non-small-cell lung cancer treated with nivolumab.

Plastin-3 (PLS3) is a circulating tumor cell marker associated with aggressive cancer phenotypes. The present study aimed to investigate the usability of plasma PLS3 concentration in assessing the diagnosis, prognosis and sensitivity to treatment in patients with non-small-cell lung cancer (NSCLC) treated with nivolumab. A total of 33 patients with recurrent or advanced NSCLC were treated with nivolumab, and 10 healthy volunteers were retrospectively enrolled. Plasma concentrations of PLS3 were determined by ELISA. Plasma PLS3 concentration in patients with NSCLC was significantly higher compared with that in healthy volunteers (median 7.64 ng/ml vs. 3.13 ng/ml, P<0.001). Univariate analysis indicated that PLS3 ≤5.43 ng/ml was a predictor of partial response. Patients with PLS3 >8.55 ng/ml exhibited a poorer prognosis compared with those in the PLS3 ≤8.55 ng/ml group. A high plasma PLS3 concentration was a predictor of poor overall survival. In conclusion, plasma PLS3 concentration was identified as a marker for the diagnosis, treatment sensitivity and prognosis in patients with NSCLC treated with nivolumab. Plasma PLS3 may be a clinically useful tumor marker in patients with NSCLC; future prospective studies may confirm these results and explore its use in other cancers.

Building SiC-based composites from polycarbosilane-derived 3D-SiC scaffolds via polymer impregnation and pyrolysis (PIP)

Direct ink writing combined with subsequent polymer impregnation and pyrolysis (PIP) was adopted to prepare 3D SiC-based composites via the polymer-derived ceramic (PDC) route. Five types of 3D SiC scaffolds with different structural parameters, i.e. fillers of inert SiC powder and active Ti powder, predesigned interconnected pores and in-situ grown SiC coatings, were fabricated and employed in the following PIP process. The PIP process exhibited linear weight-increase stage in the first ten cycles, followed by the parabolic stage with decreased weight gain rate. Interconnected pores or coated SiCw in/on the 3D scaffolds increased the interfacial bonding strength, leading to improved strength of SiC-based composites. The current work demonstrated that dense 3D PDCs with adjustable macro-/micro-structures and compositions could be achieved via direct ink writing and the following PIP process.

Wood Derived Cellulose Scaffolds-Processing and Mechanics.

Wood-derived cellulose materials obtained by structure-retaining delignification are attracting increasing attention due to their excellent mechanical properties and great potential to serve as renewable and CO2 storing cellulose scaffolds for advanced hybrid materials with embedded functionality. Various delignification protocols and a multitude of further processing steps including polymer impregnation and densification are applied resulting in a large range of properties. However, treatment optimization requires a more comprehensive characterization of the developed materials in terms of structure, chemical composition, and mechanical properties for faster progress in the field. Herein, the current protocols for structure-retaining delignification are reviewed and the emphasis is placed on the mechanical characterization at different hierarchical levels of the cellulose scaffolds by experiments and modeling to reveal the underlying structure-property relationships.

Non-destructive characterisation and evaluation of manufacturing defects in SiCf/SiC composites using the relative energy attenuation behaviour of X-rays

Silicon carbide fibre/silicon carbide (SiCf/SiC) composites are important for manufacturing the hot-section components of aero engines and supersonic vehicles. Hence, quality control, as well as qualitative and quantitative non-destructive testing and evaluation (NDT&E) are critical. A grey (G) value method for the characterisation and NDT&E of manufacturing defects in SiCf/SiC composites based on the attenuation behaviour of low-energy X-rays was proposed, and a digital X-ray imaging detection system was developed. Specimens with artificial and manufacturing defects were evaluated, thereby revealing that imperfections were induced when the SiCf/SiC composites were formed at the high-temperatures; microcracks (100-μm-wide) and rectangular defects (0.1-mm-deep) were detected with a sensitivity exceeding 100 μm. Our results demonstrated that ‘voids’, ‘microcracks’, ‘porosity’, ‘polymer impregnation inhomogeneity’, ‘fibre-lack’, and ‘gap-delamination’ were the typical manufacturing defects caused during formation of SiCf/SiC composites at high temperatures; the minimum deviation between the detected and designed length of a 10-mm-long microcrack in the 3.0-mm-thick SiCf/SiC composite specimen was ~3%; the manufacturing defects were effectively characterised and evaluated using the distribution behaviours of G values and digital radiographic imaging features.

Insights into fracture mechanisms in nanoporous gold and polymer impregnated nanoporous gold

Nanoporous metals have favourable characteristics for many applications. These materials have, however, failed to show suitable attributes in tension: showing an extremely weak and brittle response. This issue has been addressed through the impregnation of a polymer constituent into the nanoporous ligament network, creating a strong and malleable material in both tension and compression. In this work, this improvement is investigated by comparing nanoporous gold and its polymer filled nanocomposite counterpart using computational microspecimen compact-tensile tests. We examine crack initiation and propagation within these materials. The micromechanical response is also explored to reveal the influence of the polymer impregnation on fracture mechanisms. It is shown that, in agreement with the findings in the literature, the failure of a few gold ligaments in nanoporous gold leads to the complete failure of the material with a relatively small resistance to failure and a characteristically brittle fracture. Polymer impregnation, on the other hand, effectively delays the complete material failure as the polymer stabilizes the individual ligaments. This results in a significantly increased ductility under tension which is vital for it to be considered for use in structural applications.

The tuneable rubberwood: roles of impregnated polymer level

ABSTRACT This study exhibits the tuneable rubberwood with the actively controlled properties. Various amounts of polymethyl methacrylate (PMMA) were introduced into rubberwood tissues under the allowed environment. The embedded PMMA resulted to weight gaining up to about 60% and caused an increase in the density from 650 (for untreated rubberwood) to 1060 kg/m3 (for fully impregnated one). Additionally, scanning electron microscopic images revealed the evidence of the raising of PMMA amounts in the microstructure of treated rubberwood corresponding to the degrees of polymer impregnation. The embedded PMMA, from 0% to about 60% in wood tissues, enhanced water-resistant properties, i.e. the increasing in the surface contact angles for about 20 degrees, the improvement of water absorption for four times and the development of anti-swelling efficiency (ASE) for almost 20%, to the treated rubberwood. Mechanical properties, including shear, compressive and flexural strength of treated rubberwood were also gradually improved when higher levels of PMMA were incorporated into rubberwood. Moreover, the logarithm values of water absorption, ASE, shear strength and compressive strength revealed the linear tendency when the degree of impregnation was raised. This would provide an opportunity of treating rubberwood as a tuneable wood-polymer composite material for the designated applications.

Supercritical Fluid Technology and its Pharmaceutical Applications: A Revisit with Two Decades of Progress

Over the past two decades, supercritical fluid technology has emerged as one of the most important technologies applied in many fields such as cosmetic, food and pharmaceutical. Supercritical fluid extraction process offers numerous advantages such as easy, effective, inexpensive, high quality of solute extraction and environmentally friendly. This mini-review describes the fundamentals of supercritical fluid technology, the function of supercritical fluid as solvent and anti-solvent, mechanism of supercritical fluid, advantages and disadvantages and revisit the application of supercritical fluid technology in pharmaceutical sciences. In-depth discussion with recent examples of extraction of natural products, particle design in drug delivery, preparation on pharmaceutical powder, drug solubilization, inclusion complex, polymer impregnation, liposomal formulations, purification and polymorphism as well as drug extraction analysis are also presented. Key aspects and processing considerations of supercritical fluid technologies are reviewed to assist scientists to generate other related experimental works. © 2020, Association of Pharmaceutical Teachers of India. All rights reserved.

Unique, Gender-Dependent Serum microRNA Profile in PLS3 Gene-Related Osteoporosis

Plastin 3 (PLS3), encoded by PLS3, is a newly recognized regulator of bone metabolism, and mutations in the encoding gene result in severe childhood-onset osteoporosis. Because it is an X chromosomal gene, PLS3 mutation-positive males are typically more severely affected whereas females portray normal to increased skeletal fragility. Despite the severe skeletal pathology, conventional metabolic bone markers tend to be normal and are thus insufficient for diagnosing or monitoring patients. Our study aimed to explore serum microRNA (miRNA) concentrations in subjects with defective PLS3 function to identify novel markers that could differentiate subjects according to mutation status and give insight into the molecular mechanisms by which PLS3 regulates skeletal health. We analyzed fasting serum samples for a custom-designed panel comprising 192 miRNAs in 15 mutation-positive (five males, age range 8-76 years, median 41 years) and 14 mutation-negative (six males, age range 8-69 years, median 40 years) subjects from four Finnish families with different PLS3 mutations. We identified a unique miRNA expression profile in the mutation-positive subjects with seven significantly upregulated or downregulated miRNAs (miR-93-3p, miR-532-3p, miR-133a-3p, miR-301b-3p, miR-181c-5p, miR-203a-3p, and miR-590-3p; p values, range .004-.044). Surprisingly, gender subgroup analysis revealed the difference to be even more distinct in female mutation-positive subjects (congruent p values, range .007-.086) than in males (p values, range .127-.843) in comparison to corresponding mutation-negative subjects. Although the seven identified miRNAs have all been linked to bone metabolism and two of them (miR-181c-5p and miR-203a-3p) have bioinformatically predicted targets in the PLS3 3' untranslated region (3'-UTR), none have previously been reported to associate with PLS3. Our results indicate that PLS3 mutations are reflected in altered serum miRNA levels and suggest there is crosstalk between PLS3 and these miRNAs in bone metabolism. These provide new understanding of the pathomechanisms by which mutations in PLS3 lead to skeletal disease and may provide novel avenues for exploring miRNAs as biomarkers in PLS3 osteoporosis or as target molecules in future therapeutic applications. © 2020 The Authors. Journal of Bone and Mineral Research published by American Society for Bone and Mineral Research.

Polymer impregnation in porous glass beads to induce bioseparation of β-mannanase from fermentation broth of Proteus vulgaris

Polymer impregnation in porous glass beads to induce bioseparation of β-mannanase from fermentation broth of Proteus vulgaris

Biomarkers in WNT1 and PLS3 Osteoporosis: Altered Concentrations of DKK1 and FGF23.

Recent advancements in genetic research have uncovered new forms of monogenic osteoporosis, expanding our understanding of the molecular pathways regulating bone health. Despite active research, knowledge on the pathomechanisms, disease-specific biomarkers, and optimal treatment in these disorders is still limited. Mutations in WNT1, encoding a WNT/β-catenin pathway ligand WNT1, and PLS3, encoding X chromosomally inherited plastin 3 (PLS3), both result in early-onset osteoporosis with prevalent fractures and disrupted bone metabolism. However, despite marked skeletal pathology, conventional bone markers are usually normal in both diseases. Our study aimed to identify novel bone markers in PLS3 and WNT1 osteoporosis that could offer diagnostic potential and shed light on the mechanisms behind these skeletal pathologies. We measured several parameters of bone metabolism, including serum dickkopf-1 (DKK1), sclerostin, and intact and C-terminal fibroblast growth factor 23 (FGF23) concentrations in 17 WNT1 and 14 PLS3 mutation-positive subjects. Findings were compared with 34 healthy mutation-negative subjects from the same families. Results confirmed normal concentrations of conventional metabolic bone markers in both groups. DKK1 concentrations were significantly elevated in PLS3 mutation-positive subjects compared with WNT1 mutation-positive subjects (p < .001) or the mutation-negative subjects (p = .002). Similar differences were not seen in WNT1 subjects. Sclerostin concentrations did not differ between any groups. Both intact and C-terminal FGF23 were significantly elevated in WNT1 mutation-positive subjects (p = .039 and p = .027, respectively) and normal in PLS3 subjects. Our results indicate a link between PLS3 and DKK1 and WNT1 and FGF23 in bone metabolism. The normal sclerostin and DKK1 levels in patients with impaired WNT signaling suggest another parallel regulatory mechanism. These findings provide novel information on the molecular networks in bone. Extended studies are needed to investigate whether these biomarkers offer diagnostic value or potential as treatment targets in osteoporosis. © 2020 American Society for Bone and Mineral Research.