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1.
BMC Musculoskelet Disord ; 22(1): 654, 2021 Aug 02.
Artigo em Inglês | MEDLINE | ID: mdl-34340671

RESUMO

OBJECTIVE: Mechanic strength, pore morphology and size are key factors for the three-dimensional (3D) printing of porous titanium scaffolds, therefore, developing optimal structure for the 3D printed titanium scaffold to fill bone defects in knee joints is instructive and important. METHODS: Structural models of titanium scaffolds with fifteen different pore unit were designed with 3D printing computer software; five different scaffold shapes were designed: imitation diamond-60°, imitation diamond-90°, imitation diamond-120°, regular tetrahedron and regular hexahedron. Each structural shape was evaluated with three pore sizes (400, 600 and 800 µm), and fifteen types of cylindrical models (size: 20 mm; height: 20 mm). Autodesk Inventor software was used to determine the strength and safety of the models by simulating simple strength acting on the knee joints. We analyzed the data and found suitable models for the design of 3D printing of porous titanium scaffolds. RESULTS: Fifteen different types of pore unit structural models were evaluated under positive pressure and lateral pressure; the compressive strength reduced when the pore size increased. Under torsional pressure, the strengths of the imitation diamond structure were similar when the pore size increased, and the strengths of the regular tetrahedron and regular hexahedron structures reduced when the pore size increased. In each case, the compressive strength of the regular hexahedron structure was highest, that of the regular tetrahedron was second highest, and that of the imitation diamond structure was relatively low. Fifteen types of cylindrical models under a set force were evaluated, and the sequence of comprehensive compressive strength, from strong to weak was: regular hexahedron > regular tetrahedron > imitation diamond-120° > imitation diamond-90° > imitation diamond-60°. The compressive strength of cylinder models was higher when the pore size was smaller. CONCLUSION: The pore size and pore morphology were important factors influencing the compressive strength. The strength of each structure reduced when the pore size (400, 600 and 800 µm) increased. The models of regular hexahedron, regular tetrahedron and imitation diamond-120°appeared to meet the conditions of large pore sizes and high compressive strength.


Assuntos
Impressão Tridimensional , Titânio , Força Compressiva , Humanos , Porosidade , Tecidos Suporte
2.
Acta Biomater ; 131: 403-414, 2021 09 01.
Artigo em Inglês | MEDLINE | ID: mdl-34245895

RESUMO

The increased risk of fracture in the elderly associated with metabolic conditions like osteoporosis poses a significant strain on health care systems worldwide. Due to bone's hierarchical nature, it is necessary to study its mechanical properties and failure mechanisms at several length scales. We conducted micropillar compression experiments on ovine cortical bone to assess the anisotropic mechanical response at the lamellar scale over a wide range of strain rates (10-4 to 8·102 s-1). At the microscale, lamellar bone exhibits a strain rate sensitivity similar to what is reported at the macroscale suggesting that it is an intrinsic property of the extracellular matrix. Significant shear band thickening was observed at high strain rates by HRSEM and STEM imaging. This is likely caused by the material's inability to accommodate the imposed deformation by propagation of thin kink bands and shear cracks at high strain rates, leading to shear band thickening and nucleation. The post-yield behavior is strain rate and direction dependent: hardening was observed for transverse oriented micropillars and hardening modulus increases with strain rate by a factor of almost 2, while axially oriented micropillars showed strain softening and an increase of the softening peak width and work to ultimate stress as a function of strain rate. This suggests that for compression at the micrometer scale, energy absorption in bone increases with strain rate. This study highlights the importance of investigating bone strength and post-yield behavior at lower length scales, under hydrated conditions and at clinically relevant strain rates. STATEMENT OF SIGNIFICANCE: We performed micropillar compression experiments of ovine cortical bone at two different orientations and over seven orders of magnitude of strain rate. Experiments were performed under humid condition to mimic the natural conditions of bone in a human body using a newly developed micro-indenter setup. The strain rate sensitivity was found to be of a similar magnitude to what has been reported for higher length scales, suggesting that the strain rate sensitivity is an intrinsic property of the bone extracellular matrix. In addition, localized shear deformation in thick bands was observed for the first time at high strain rates, highlighting the importance of investigating bone under conditions representative of an accident or fall at several length scales.


Assuntos
Osso e Ossos , Osso Cortical , Idoso , Animais , Força Compressiva , Matriz Extracelular , Humanos , Pressão , Ovinos , Estresse Mecânico
3.
J Environ Manage ; 297: 113238, 2021 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-34274769

RESUMO

Wastewater (sewage) treatment plants generate a high volume of sludge that, although it is classified as class II-A (not inert) non-hazardous waste, is commonly disposed of in sanitary landfills. Hence the environmental urge to assess its valorization possibilities. The present study describes the use of a sewage sludge as raw material in the production of red ceramic bricks by extrusion, focusing on the technological changes brought about by the presence of the sludge during the plastic forming process, in terms of the plasticity of the mixture and its subsequent extrudability. To quantitatively identify the best moisture conditions for the extrusion of high-quality products, shear strain amplitude sweep (torsional) tests were conducted on green (moist) prismatic samples produced with different moisture and sludge contents. For sewage sludge contents up to 10 wt%, the optimal moisture content was identified at 31-33 wt%. Higher water demand was identified for 15 wt% of sludge, for which optimal extrusion results required 35 wt% moisture. The total linear shrinkage after drying and firing, as well as the water absorption, were within the limits required for ceramic bricks for all the sludge contents. The results for compressive strength of the fired bricks also demonstrate that the incorporation of up to 15 wt% sewage sludge into the clay mixture is highly feasible for the production of extruded ceramic bricks.


Assuntos
Materiais de Construção , Esgotos , Cerâmica , Argila , Força Compressiva
4.
Int J Mol Sci ; 22(14)2021 Jul 07.
Artigo em Inglês | MEDLINE | ID: mdl-34298923

RESUMO

In the following study, polyurethane (PUR) composites were modified with 2 wt.% of walnut shell filler modified with selected mineral compounds-perlite, montmorillonite, and halloysite. The impact of modified walnut shell fillers on selected properties of PUR composites, such as rheological properties (dynamic viscosity, foaming behavior), mechanical properties (compressive strength, flexural strength, impact strength), dynamic-mechanical behavior (glass transition temperature, storage modulus), insulation properties (thermal conductivity), thermal characteristic (temperature of thermal decomposition stages), and flame retardant properties (e.g., ignition time, limiting oxygen index, heat peak release) was investigated. Among all modified types of PUR composites, the greatest improvement was observed for PUR composites filled with walnut shell filler functionalized with halloysite. For example, on the addition of such modified walnut shell filler, the compressive strength was enhanced by ~13%, flexural strength by ~12%, and impact strength by ~14%. Due to the functionalization of walnut shell filler with thermally stable flame retardant compounds, such modified PUR composites were characterized by higher temperatures of thermal decomposition. Most importantly, PUR composites filled with flame retardant compounds exhibited improved flame resistance characteristics-in all cases, the value of peak heat release was reduced by ~12%, while the value of total smoke release was reduced by ~23%.


Assuntos
Óxido de Alumínio/química , Bentonita/química , Argila/química , Resinas Compostas/química , Juglans/química , Poliuretanos/química , Dióxido de Silício/química , Força Compressiva , Vidro/química , Teste de Materiais/métodos , Temperatura , Viscosidade
5.
J Mech Behav Biomed Mater ; 122: 104668, 2021 10.
Artigo em Inglês | MEDLINE | ID: mdl-34265671

RESUMO

The objectives of this study were to develop novel methods for quantifying human rib cortical bone material properties in compression and to compare the compressive material property data to existing tensile data for matched subjects. Cylindrical coupons were obtained from the rib cortical bone of 30 subjects (M = 19, F = 11) ranging from 18 to 95 years of age (Avg. = 48.5 ± 24.3). Two coupons were obtained from each subject. One coupon was tested in compression at 0.005 strain/s, while the other coupon was tested in compression at 0.5 strain/s. Load and displacement data were recorded so that the elastic modulus, yield stress, yield strain, ultimate stress, ultimate strain, elastic strain energy density (SED), plastic SED, and total SED could be calculated. All compressive material properties were significantly different between the two loading rates. An ANOVA revealed that sex alone had no significant effect on the compressive material properties. The interaction between sex and age was significant for some material properties, but this may have been a consequence of the lack of older females in the subject pool. None of the compressive material properties were significantly correlated with age, but were more correlated with sample density. This finding differed for the tensile material properties, which showed stronger correlations with age. When comparing between tension and compression, significant differences were observed for all material properties except for the total SED, once the effects of loading rate and age had been accounted for. This was the first study to quantify the material properties of human rib cortical bone in compression. The results of this study demonstrated that rib and thorax finite element models should consider the effects of loading rate, loading mode, and age when incorporating material properties published in the literature.


Assuntos
Osso Cortical , Costelas , Força Compressiva , Módulo de Elasticidade , Feminino , Humanos , Estresse Mecânico , Tórax
6.
Int J Mol Sci ; 22(11)2021 Jun 04.
Artigo em Inglês | MEDLINE | ID: mdl-34199865

RESUMO

In obese patients, enhanced serum levels of free fatty acids (FFA), such as palmitate (PA) or oleate (OA), are associated with an increase in systemic inflammatory markers. Bacterial infection during periodontal disease also promotes local and systemic low-grade inflammation. How both conditions concomitantly impact tooth movement is largely unknown. Thus, the aim of this study was to address the changes in cytokine expression and the secretion of human periodontal ligament fibroblasts (HPdLF) due to hyperlipidemic conditions, when additionally stressed by bacterial and mechanical stimuli. To investigate the impact of obesity-related hyperlipidemic FFA levels on HPdLF, cells were treated with 200 µM PA or OA prior to the application of 2 g/cm2 compressive force. To further determine the additive impact of bacterial infection, HPdLF were stimulated with lipopolysaccharides (LPS) obtained from Porphyromonas gingivalis. In mechanically compressed HPdLF, PA enhanced COX2 expression and PGE2 secretion. When mechanically stressed HPdLF were additionally stimulated with LPS, the PGE2 and IL6 secretion, as well as monocyte adhesion, were further increased in PA-treated cultures. Our data emphasize that a hyperlipidemic condition enhances the susceptibility of HPdLF to an excessive inflammatory response to compressive forces, when cells are concomitantly exposed to bacterial components.


Assuntos
Fibroblastos/imunologia , Hiperlipidemias/fisiopatologia , Inflamação/imunologia , Lipopolissacarídeos/farmacologia , Ligamento Periodontal/imunologia , Porphyromonas gingivalis/química , Estresse Mecânico , Força Compressiva , Citocinas/metabolismo , Fibroblastos/efeitos dos fármacos , Fibroblastos/patologia , Humanos , Inflamação/induzido quimicamente , Inflamação/patologia , Ligamento Periodontal/efeitos dos fármacos , Ligamento Periodontal/patologia , Pressão
7.
AAPS PharmSciTech ; 22(5): 201, 2021 Jul 06.
Artigo em Inglês | MEDLINE | ID: mdl-34231193

RESUMO

Particle engineering of excipients, at sub-particulate level using co-processing, can provide high functionality excipients. NanoCrySP technology has been recently explored as a novel approach for the generation of nanocrystalline solid dispersion of poorly soluble drugs, using spray drying process. The purpose of the present study was to generate co-processed mannitol and sorbitol (SD-CSM) using NanoCrySP technology having similar composition to commercial co-processed excipient (Compressol® SM, CP). The characterization of excipients was performed to evaluate their various physicomechanical properties. The sub-micron crystallite size of sorbitol in the matrix of mannitol was determined using the Williamson-Hall equation and Halder-Wagner equation. The reduction in crystallite size of sorbitol and mannitol, lower melting point, and lower heat of fusion of SD-CSM could be responsible for excellent compactibility, better tabletability, and comparable compressibility with respect to CP. This was confirmed by the compressibility-tabletability-compactibility (CTC) profile and Heckel plot analysis. Overall, SD-CSM generated using NanoCrySP technology improved functionalities of excipients over CP and would be useful for direct compression application.


Assuntos
Composição de Medicamentos/métodos , Manitol/química , Nanotecnologia , Sorbitol/química , Força Compressiva , Cristalização , Excipientes/química , Tamanho da Partícula , Porosidade , Comprimidos/química , Resistência à Tração , Molhabilidade
8.
Molecules ; 26(11)2021 May 28.
Artigo em Inglês | MEDLINE | ID: mdl-34071673

RESUMO

Calcium phosphate cements have the advantage that they can be prepared as a paste that sets in a few minutes and can be easily adapted to the shape of the bone defect, which facilitates its clinical application. In this research, six formulations of brushite (dicalcium phosphate dihydrated) cement were obtained and the effect of the addition of sodium alginate was analyzed, such as its capacity as a tetracycline release system. The samples that contain sodium alginate set in 4 or 5 min and showed a high percentage of injectability (93%). The cements exhibit compression resistance values between 1.6 and 2.6 MPa. The drug was released in a range between 12.6 and 13.2% after 7 days. The antimicrobial activity of all the cements containing antibiotics was proven. All samples reached values of cell viability above 70 percent. We also observed that the addition of the sodium alginate and tetracycline improved the cell viability.


Assuntos
Alginatos/química , Cimentos Ósseos/química , Fosfatos de Cálcio/química , Tetraciclina/farmacologia , Células 3T3-L1 , Animais , Antibacterianos/química , Materiais Biocompatíveis/química , Regeneração Óssea , Proliferação de Células , Sobrevivência Celular , Força Compressiva , Concentração de Íons de Hidrogênio , Camundongos , Microscopia Eletrônica de Varredura , Microscopia Eletrônica de Transmissão , Pressão , Estresse Mecânico , Tetraciclina/química , Fatores de Tempo , Engenharia Tecidual , Difração de Raios X
9.
Environ Sci Pollut Res Int ; 28(28): 37110-37119, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-34075497

RESUMO

Nanotechnology has opened up a plethora of opportunities and has acquired extreme importance in a myriad of fields to produce enhanced materials. Their special properties make them sustainable for industrial purposes. One of the most crucial processes in the petroleum and geothermal industries is cementing. Various classes of Portland cement are used according to API classifications. The conventional Portland cement fails to perform its function at high pressure and high temperature (HPHT) conditions. Hence, various admixtures are used to improve its properties. HPHT conditions not only have a bad impact on Portland cement by affecting its rheological properties but also reduce its strength, porosity, and permeability. So, additives like nano silica are used to improve its properties. Better compressive strength, low porosity and permeability, higher yield stress, and reduced setting time are some of the major properties that improve by the use of nano silica. This paper discusses in detail the different types of cement, cementing processes, failure of Portland cement, and effect of nano silica as an admixture on the compressive strength, rheology, porosity, and permeability of the cement. Furthermore, the upcoming challenges in cementing are discussed along with future potential in this field.


Assuntos
Campos de Petróleo e Gás , Dióxido de Silício , Força Compressiva , Materiais de Construção , Porosidade
10.
Molecules ; 26(11)2021 May 31.
Artigo em Inglês | MEDLINE | ID: mdl-34072622

RESUMO

Lipid membranes are common to all forms of life. While being stable barriers that delimitate the cell as the fundamental organismal unit, biological membranes are highly dynamic by allowing for lateral diffusion, transbilayer passage via selective channels, and in eukaryotic cells for endocytic uptake through the formation of membrane bound vesicular or tubular carriers. Two of the most abundant fundamental fabrics of membranes-lipids and complex sugars-are produced through elaborate chains of biosynthetic enzymes, which makes it difficult to study them by conventional reverse genetics. This review illustrates how organic synthesis provides access to uncharted areas of membrane glycobiology research and its application to biomedicine. For this Special Issue on Chemical Biology Research in France, focus will be placed on synthetic approaches (i) to study endocytic functions of glycosylated proteins and lipids according to the GlycoLipid-Lectin (GL-Lect) hypothesis, notably that of Shiga toxin; (ii) to mechanistically dissect its endocytosis and intracellular trafficking with small molecule; and (iii) to devise intracellular delivery strategies for immunotherapy and tumor targeting. It will be pointed out how the chemical biologist's view on lipids, sugars, and proteins synergizes with biophysics and modeling to "look" into the membrane for atomistic scale insights on molecular rearrangements that drive the biogenesis of endocytic carriers in processes of clathrin-independent endocytosis.


Assuntos
Endocitose , Glicolipídeos/química , Lectinas/química , Lipídeos/química , Animais , Transporte Biológico , Membrana Celular/metabolismo , Força Compressiva , França , Galectinas/química , Glicômica/tendências , Glicoesfingolipídeos/química , Glicosilação , Humanos , Imunoterapia/métodos , Modelos Biológicos , Neoplasias/terapia , Transporte Proteico , Toxina Shiga/química , Estresse Mecânico
11.
Mater Sci Eng C Mater Biol Appl ; 126: 112140, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-34082951

RESUMO

Multiscale 3D carbon architectures are of particular interest in tissue engineering applications, as these structures may allow for three-dimensional cell colonization essential for tissue growth. In this work, carbon fiber/microlattice hybrid architectures are introduced as innovative multi-scale scaffolds for tissue engineering. The microlattice provides the design freedom and structural integrity, whereas the fibrous component creates a cellular microenvironment for cell colonization. The hybrid structures are fabricated by carbonization of stereolithographically 3D printed epoxy microlattice architectures which are pre-filled with cotton fibers within the empty space of the architectures. The cotton filling result in less shrinkage of the architecture during carbonization, as the tight confinement of the fibrous material prevents the free-shrinkage of the microlattices. The hybrid architecture exhibits a compressive strength of 156.9±25.6 kPa, which is significantly higher than an empty carbon microlattice architecture. Furthermore, the hybrid architecture exhibits a flexible behavior up to 30% compressive strain, which is also promising towards soft-tissue regeneration. Osteoblast-like murine MC3T3-E1 cells are cultured within the 3D hybrid structures. Results show that the cells are able to not only proliferate on the carbon microlattice elements as well as along the carbon fibers, but also make connections with each other across the inner pores created by the fibers, leading to a three-dimensional cell colonization. These carbon fiber/microlattice hybrid structures are promising for future fabrication of functionally graded scaffolds for tissue repair applications.


Assuntos
Engenharia Tecidual , Tecidos Suporte , Animais , Fibra de Carbono , Força Compressiva , Camundongos , Osteoblastos , Impressão Tridimensional
12.
Int J Mol Sci ; 22(9)2021 Apr 30.
Artigo em Inglês | MEDLINE | ID: mdl-33946213

RESUMO

In the following study, ground plum stones and silanized ground plum stones were used as natural fillers for novel polyurethane (PUR) composite foams. The impact of 1, 2, and 5 wt.% of fillers on the cellular structure, foaming parameters, and mechanical, thermomechanical, and thermal properties of produced foams were assessed. The results showed that the silanization process leads to acquiring fillers with a smoother surface compared to unmodified filler. The results also showed that the morphology of the obtained materials is affected by the type and content of filler. Moreover, the modified PUR foams showed improved properties. For example, compared with the reference foam (PUR_REF), the foam with the addition of 1 wt.% of unmodified plum filler showed better mechanical properties, such as higher compressive strength (~8% improvement) and better flexural strength (~6% improvement). The addition of silanized plum filler improved the thermal stability and hydrophobic character of PUR foams. This work shows the relationship between the mechanical, thermal, and application properties of the obtained PUR composites depending on the modification of the filler used during synthesis.


Assuntos
Poliuretanos/química , Prunus domestica/química , Silanos/química , Técnicas de Química Sintética , Força Compressiva , Materiais de Construção , Teste de Materiais , Poliuretanos/síntese química , Porosidade , Reologia , Silanos/síntese química
13.
Int J Biol Macromol ; 182: 1704-1712, 2021 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-34052269

RESUMO

Designing clinical applicable polymeric composite scaffolds for auricular cartilage tissue engineering requires appropriate mechanical strength and biological characteristics. In this study, silk fiber-based scaffolds co-reinforced with poly-L-lactic acid porous microspheres (PLLA PMs) combined with either Bombyx mori (Bm) or Antheraea pernyi (Ap) silk fibers were fabricated as inspired by the "steel bars reinforced concrete" structure in architecture and their chondrogenic functions were also investigated. We found that the Ap silk fiber-based scaffolds reinforced by PLLA PMs (MAF) exhibited superior physical properties (the mechanical properties in particular) as compared to the Bm silk fiber-based scaffolds reinforced by PLLA PMs (MBF). Furthermore, in vitro evaluation of chondrogenic potential showed that the MAF provided better cell adhesion, viability, proliferation and GAG secretion than the MBF. Therefore, the MAF are promising in auricular cartilage tissue engineering and relevant plastic surgery-related applications.


Assuntos
Cartilagem da Orelha/fisiologia , Microesferas , Morus/química , Poliésteres/química , Seda/química , Tecidos Suporte/química , Animais , Bombyx , Proliferação de Células , Forma Celular , Sobrevivência Celular , Condrócitos/citologia , Condrócitos/metabolismo , Força Compressiva , DNA/metabolismo , Regulação da Expressão Gênica , Glicosaminoglicanos/metabolismo , Porosidade , Coelhos , Seda/ultraestrutura , Fator de Necrose Tumoral alfa/metabolismo
14.
Int J Biol Macromol ; 182: 1746-1758, 2021 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-34052276

RESUMO

Amino-functionalized mesoporous silica nanoparticles with radially porous architecture were optimally synthesized, and they were used together with silk fibroin and chitosan to produce a type of covalently crosslinked composite hydrogel using genipin as a crosslinker. The optimally achieved composite gels were found to be thermo-responsive at physiological temperature and pH with well-defined injectability. They were also detected to have mechanically strong and elastic characteristics. In addition, these gels showed the ability to release bioactive Si ions suited to an effective dose range in approximately linear manners for a few weeks. Studies on the cell-gel constructs revealed that the composite gels well supported the growth of seeded MC3T3-E1 cells, and the deposition of matrix components. Results obtained from the detection of alkaline phosphatase activity and the matrix mineralization in the cell-gel constructs confirmed that these composite gels had certain osteogenic capacity. The obtained results suggest that these composite gels have promising potential in bone repair and regeneration.


Assuntos
Osso e Ossos/fisiologia , Quitosana/química , Elasticidade , Fibroínas/química , Hidrogéis/química , Dióxido de Silício/química , Temperatura , Engenharia Tecidual , Animais , Apatitas/metabolismo , Linhagem Celular , Proliferação de Células , Sobrevivência Celular , Força Compressiva , Reagentes para Ligações Cruzadas/química , Íons , Camundongos , Nanopartículas/química , Nanopartículas/ultraestrutura , Porosidade
15.
J Mater Chem B ; 9(18): 3826-3837, 2021 05 14.
Artigo em Inglês | MEDLINE | ID: mdl-33979417

RESUMO

"Self-fitting" shape memory polymer (SMP) scaffolds prepared as semi-interpenetrating networks (semi-IPNs) with crosslinked linear-poly(ε-caprolactone)-diacrylate (PCL-DA, Mn∼10 kg mol-1) and linear-poly(l-lactic acid) (PLLA, Mn∼15 kg mol-1) [75/25 wt%] exhibited robust mechanical properties and accelerated degradation rates versus a PCL-DA scaffold control. However, their potential to treat irregular craniomaxillofacial (CMF) bone defects is limited by their relatively high fitting temperature (Tfit∼55 °C; related to the Tm of PCL) required for shape recovery (i.e. expansion) and subsequent shape fixation during press fitting of the scaffold, which can be harmful to surrounding tissue. Additionally, the viscosity of the solvent-based precursor solutions, cast over a fused salt template during fabrication, can limit scaffold size. Thus, in this work, analogous semi-IPN SMP scaffolds were formed with a 4-arm star-PCL-tetracryalate (star-PCL-TA) (Mn∼10 kg mol-1) and star-PLLA (Mn∼15 kg mol-1). To assess the impact of a star-polymer architecture, four semi-IPN compositions were prepared: linear-PCL-DA/linear-PLLA (L/L), linear-PCL-DA/star-PLLA (L/S), star-PCL-TA/linear-PLLA (S/L) and star-PCL-TA/star-PLLA (S/S). Two PCL controls were also prepared: LPCL (i.e. 100% linear-PCL-DA) and SPCL (i.e. 100% star-PCL-TA). The S/S semi-IPN scaffold exhibited particularly desirable properties. In addition to achieving a lower, tissue-safe Tfit (∼45 °C), it exhibited the fastest rate of degradation which is anticipated to more favourably permit neotissue infiltration. The radial expansion pressure exerted by the S/S semi-IPN scaffold at Tfit was greater than that of LPCL, which is expected to enhance osseointegration and mechanical stability. The intrinsic viscosity of the S/S semi-IPN macromer solution was also reduced such that larger scaffold specimens could be prepared.


Assuntos
Materiais Inteligentes/química , Animais , Doenças Ósseas/terapia , Força Compressiva , Modelos Animais de Doenças , Poliésteres/química , Porosidade , Ratos , Materiais Inteligentes/metabolismo , Materiais Inteligentes/uso terapêutico , Viscosidade
16.
Int J Biol Macromol ; 184: 170-180, 2021 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-34052273

RESUMO

Bone defect is usually difficult to recover quickly, and bone scaffold transplantation is considered to be an effective method. Biomaterials have a wide range of application prospects in bone tissue repair, and the two key problems are the selection of materials and cells. The object of this study was to discuss the structural characteristics of bone scaffold materials and their effects on bone repair in vivo. The chitin-hydroxyapatite (HAP)-collagen composite scaffolds (CHCS) was prepared with epichlorohydrin (ECH) as crosslinking agent. The structure was characterized and the compressive strength, porosity, water absorbency and stability were investigated. The biocompatibility and osteogenic differentiation of CHCS in vitro were detected, and the effect of defect repair in vivo was evaluated. The results suggested that HAP not only enhanced the compressive strength of CHCS, but also promoted the formation of calcium nodules due to its bone conductivity. Histological staining showed that collagen promoted collagen deposition and new bone formation. X-ray images also indicated that CHCS transplantation accelerated bone repair. Therefore, CHCs has immense potential in bone regeneration.


Assuntos
Materiais Biocompatíveis/farmacologia , Regeneração Óssea/efeitos dos fármacos , Osso e Ossos/lesões , Quitina/química , Colágeno/química , Durapatita/farmacologia , Animais , Materiais Biocompatíveis/química , Osso e Ossos/efeitos dos fármacos , Osso e Ossos/metabolismo , Diferenciação Celular , Linhagem Celular , Força Compressiva , Durapatita/química , Epicloroidrina/química , Masculino , Células-Tronco Mesenquimais/citologia , Camundongos , Osteogênese/efeitos dos fármacos , Porosidade , Ratos , Engenharia Tecidual , Tecidos Suporte
17.
J R Soc Interface ; 18(178): 20210040, 2021 05.
Artigo em Inglês | MEDLINE | ID: mdl-33975461

RESUMO

Climbing plants must reach supports and navigate gaps to colonize trees. This requires a structural organization ensuring the rigidity of so-called 'searcher' stems. Cacti have succulent stems adapted for water storage in dry habitats. We investigate how a climbing cactus Selenicereus setaceus develops its stem structure and succulent tissues for climbing. We applied a 'wide scale' approach combining field-based bending, tensile and swellability tests with fine-scale rheological, compression and anatomical analyses in laboratory conditions. Gap-spanning 'searcher' stems rely significantly on the soft cortex and outer skin of the stem for rigidity in bending (60-94%). A woody core contributes significantly to axial and radial compressive strength (80%). Rheological tests indicated that storage moduli were consistently higher than loss moduli indicating that the mucilaginous cortical tissue behaved like a viscoelastic solid with properties similar to physical or chemical hydrogels. Rheological and compression properties of the soft tissue changed from young to old stages. The hydrogel-skin composite is a multi-functional structure contributing to rigidity in searcher stems but also imparting compliance and benign failure in environmental situations when stems must fail. Soft tissue composites changing in function via changes in development and turgescence have a great potential for exploring candidate materials for technical applications.


Assuntos
Cactaceae , Força Compressiva , Hidrogéis , Pressão , Árvores
18.
AAPS PharmSciTech ; 22(4): 151, 2021 May 11.
Artigo em Inglês | MEDLINE | ID: mdl-33977355

RESUMO

As commonly known, the product development stage is quite complex, requires intensive knowledge, and is time-consuming. The selection of the excipients with the proper functionality and their corresponding levels is critical to drug product performance. The objective of this study was to apply quality by design (QbD) principles for formulation development and to define the desired product quality profile (QTPP) and critical quality attributes (CQA) of a product. QbD is a risk- and science-based holistic approach for upgraded pharmaceutical development. In this study, Ibuprofen DC 85W was used as a model drug, Cellactose® 80 along with MicroceLac® 100 as a filler, and magnesium stearate, stearic acid, and sodium stearyl fumarate as lubricants. By applying different formulation parameters to the filler and lubricants, the QbD approach furthers the understanding of the effect of critical formulation and process parameters on CQAs and the contribution to the overall quality of the drug product. An experimental design study was conducted to determine the changes of the obtained outputs of the formulations, which were evaluated using the Modde Pro 12.1 statistical computer program that enables optimization by modeling complex relationships. The results of the optimum formulation revealed that MicroceLac® 100 was the superior filler, while magnesium stearate at 1% was the optimum lubricant. A design space that indicates the safety operation limits for the process and formulation variables was also created. This study enriches the understanding of the effect of excipients in formulation and assists in enhancing formulation design using experimental design and mathematical modeling methods in the frame of the QbD approach.


Assuntos
Química Farmacêutica/métodos , Força Compressiva , Desenvolvimento de Medicamentos/métodos , Lubrificantes/síntese química , Química Farmacêutica/normas , Composição de Medicamentos/métodos , Desenvolvimento de Medicamentos/normas , Ibuprofeno/síntese química , Ibuprofeno/normas , Lubrificantes/normas , Ácidos Esteáricos/síntese química , Ácidos Esteáricos/normas , Tensoativos/síntese química , Tensoativos/normas , Comprimidos , Resistência à Tração
19.
Environ Sci Pollut Res Int ; 28(35): 49074-49088, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-33928510

RESUMO

Research for alternative binders has become a necessity due to cement's embodied carbon, climate change, and depletion of natural resources. These binders could potentially reduce our reliance on cement as the sole binder for concrete while simultaneously enhancing the functional characteristics of concrete. Theoretically, the use of finer particles in the cement matrix densifies the pore structure of concrete and results in improved properties. To validate this hypothesis, current research was designed to investigate how the value-added benefits of nano-silica (NS) and metakaolin (MK) in fly ash (FA)-blended cement affect the mechanical and durability characteristics of concrete when used as ternary and quaternary blends. Additionally, the cost-benefit analysis and environmental impact assessment were conducted. It was observed that the synergy of MK and NS used in FA-blended cement had a greater impact on enhancing the functional characteristics of concrete, while 10% MK as ordinary Portland cement (OPC) replacement and 1% NS as an additive in FA-blended OPC concrete was the optimum combination which achieved 94-MPa compressive strength at the age of 91 days and showed more than 25% increment in the flexural and splitting tensile strengths compared to the control mix (MS00). The ultrasonic pulse velocity and dynamic modulus of elasticity were significantly improved, while a significant reduction in chloride migration of 50% was observed. In terms of environmental impact, MS100 (30% FA and 10% MK) exhibited the least embodied CO2 emissions of 319.89 kgCO2/m3, while the highest eco-strength efficiency of 0.268 MPa/kgCO2·m-3 with respect to 28-day compressive strength was exhibited by MS101. In terms of cost-benefit, MS00 was determined the cheapest, while the addition of MK and NS increased the cost. The lowest cost of producing 1 MPa was exhibited by MS01 with a merely 0.04-$/MPa/m3 reduction compared to MS00.


Assuntos
Carbono , Cinza de Carvão , Força Compressiva , Materiais de Construção , Dióxido de Silício
20.
Hum Mov Sci ; 77: 102793, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-33845277

RESUMO

The study aimed to investigate the control and coordination of grip force (normal component) and load force (tangential component) in three different manipulation tasks in individuals with diabetes with and with no diagnosis of diabetic peripheral neuropathy (DPN) and healthy controls. Twenty-four individuals with type 2 diabetes mellitus, 12 with no (nDPN) and 12 with DPN (wDPN), and 12 healthy controls performed three manipulation tasks (static holding, lifting and holding, and oscillation) with the dominant hand, using an instrumented handle. Relative safety margin (% of GF exerted above the minimum GF needed to hold the object) was measured in all tasks. Individuals with diabetes from the nDPN and wDPN groups set lower relative safety margin than controls only in the static holding task. No other group effect was revealed, except a lower coefficient of friction between skin and object surface in individuals with DPN. The coordination between grip and load force and grip force control was not affected by the diabetes during dynamic manipulation tasks (lifting and holding and oscillation). However, when individuals with diabetes without and with DPN performed a manipulation task in which the inflow of cutaneous information was small and stable (static holding), grip force control was affected by the disease. This finding indicates that individuals with type 2 diabetes mellitus not diagnosed with DPN, already show mild impairments in the nervous system that could affect grip force control and that could be one of the first signs of neuropathy caused by the diabetes.


Assuntos
Diabetes Mellitus Tipo 2/fisiopatologia , Neuropatias Diabéticas/fisiopatologia , Força da Mão/fisiologia , Estresse Mecânico , Adulto , Idoso , Antropometria , Sistema Nervoso Central , Força Compressiva , Feminino , Fricção , Humanos , Masculino , Pessoa de Meia-Idade , Oscilometria , Reprodutibilidade dos Testes , Segurança , Pele
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