Abstract Additive manufacturing (AM) technology from engineering has helped to achieve several advances in the medical field, particularly as far as fabrication of implants is concerned. The use of ...AM has made it possible to carry out surgical planning and simulation using a three-dimensional physical model which accurately represents the patient's anatomy. AM technology enables the production of models and implants directly from a 3D virtual model, facilitating surgical procedures and reducing risks. Furthermore, AM has been used to produce implants designed for individual patients in areas of medicine such as craniomaxillofacial surgery, with optimal size, shape and mechanical properties. This work presents AM technologies which were applied to design and fabricate a biomodel and customized implant for the surgical reconstruction of a large cranial defect. A series of computed tomography data was obtained and software was used to extract the cranial geometry. The protocol presented was used to create an anatomic biomodel of the bone defect for surgical planning and, finally, the design and manufacture of the patient-specific implant.
The spin-spray layer-by-layer (SS-LBL) deposition technique was utilized to produce multilayer films of poly(acrylic acid) (PAA)/poly(ethylene imine) (PEI) with and without nanoparticles of layered ...double hydroxides (LDH), and the structure and gas barrier properties of the films were compared with those produced by the dipping layer-by-layer technique (dipping-LBL). The thickness growth of dipping-LBL films is clearly exponential, whereas the SS-LBL films exhibited a lower growth rate. Microscopy analysis revealed that the roughness is much lower, and the orientation and planarization of the LDH nanoplatelets is higher, in SS-LBL films than in dipping-LBL films. LBL films deposited on PET substrates resulted in large reductions in the gas permeabilities compared with neat PET, and this barrier effect is more intense for films deposited by SS-LBL containing LDH nanoparticles. For these films, oxygen and carbon dioxide gas permeation reductions of about 10× and 50×, respectively, were observed after only 5 deposition cycles of the sequence (PEI/PAA/LDH/PAA). Besides the higher efficiency of SS-LBL in decreasing the gas permeability, this deposition technique is also 20 times faster than dipping-LBL, and the coated films have higher light transmittance. This combination of high gas barrier, fast assembly, and high optical clarity of polymer/LDH composite nanocoatings is expected to be very attractive in the production of films for food packaging and electronic encapsulation applications.
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•Gas barrier nanocoatings were synthesized via dipping and spin-spray LBL techniques.•Spin-spray LBL technique was found to be about 20× faster than dipping LBL.•Gas barrier of spin-spray LBL coatings is superior than dipping LBL ones.•70 nm thick nanocoating containing LDH nanoparticles improves >50× the CO2 barrier.
In a nutshell: prospects and challenges on coatings for edible kernels Azeredo, Henriette Monteiro Cordeiro; Otoni, Caio Gomide; Assis, Odilio Benedito Garrido ...
Journal of the science of food and agriculture,
April 2020, 2020-Apr, 2020-04-00, 20200401, Letnik:
100, Številka:
6
Journal Article
Combining spectroscopic techniques with electrochemistry is a promising strategy, as it allows the detailed investigation of the species that are consumed and produced by the reaction in real time. ...However, as with any in situ coupling technique, the junction between NMR and electrochemistry presents some challenges, notably the distortion of NMR signals due to the placement of electrodes close to or within the detection region. In this work, miniaturized electrodes made of carbon fiber paper were developed and later modified with platinum. Platinum decoration by cathodic deposition was chosen, as platinum is a prominent element in electrocatalysis, able to catalyze a large variety of reactions. To evaluate the efficiency of this electrochemical system, the oxidation of ascorbic acid was used as a model reaction. It was observed that the electrodes caused substantial signal distortion when placed within the detection region (full width at half-maximum equal to 1.46 Hz), whereas no distortion was observed when the electrodes were placed 1 mm above the detection region (full width at half-maximum equal to 0.95 Hz). With this system, it was also possible to monitor the magnetoelectrolysis effect, caused by the interaction of the magnetic field with the flowing ions, leading to a doubling of the ascorbic acid oxidation rate, compared to the reaction performed without a magnetic field. In addition to its low cost and simplicity in preparation, the developed electrode system allows the electrode surface to be easily modified with other suitable catalysts.
The objective of this study is to evaluate the influence of different chemical surface treatments (H3PO4, HNO3, and NaOH) in the formation of calcium phosphate phases on the surface of Al2O3/ZrO2 ...(5vol%) nanocomposite. For this purpose, Al2O3/ZrO2 samples were shaped, calcined at 400°C, sintered at 1500°C, subjected to different chemical treatments, and biomimetically coated from 14 to 21 days. Surface characterization was performed by scanning electron microscopy, atomic force microscopy, confocal microscopy, X-ray diffraction, and infrared spectroscopy. It was observed that the preliminary chemical treatment favored the formation of particular calcium phosphate phases of interest, such as α-TCP (alpha-tricalcium phosphate), β-TCP (beta-tricalcium phosphate), and HA (hydroxyapatite). The differences among the percentages of the phases formed affected the homogeneity of calcium phosphate distribution within the nanocomposites as well as the roughness of the formed layer, effectively contributing to adhesion, proliferation, and desired cell biofixation on bone implant.
During the shelf-life of fresh meat, physical, chemical, microbiological, and sensory changes may occur. To avoid such changes, the combination of vacuum-packaging and use of edible coatings make a ...good strategy. This study aimed to evaluate the physicochemical characteristics of vacuum-packaged lamb meat combined with different zein-based edible coatings containing different vegetable oils (pink pepper, rosemary, olive oil, and the combinations of olive oil + pink pepper or rosemary), stored at 5 ± 1 °C. Parameters including pH, instrumental color, water holding capacity (WHC), shear force, and thiobarbituric acid reactive substances (TBARS) were analyzed every seven days, for 29 days. Significant differences (P<0.05) were observed in coating effects and storage time. The combination of olive oil and pepper oil (OLPP) exhibited higher color stability, while the coatings containing rosemary (RO), rosemary and olive oil (OLRO), and pink pepper oil (PP) exhibited the highest oxidative stability in 29 days. The pH, WHC, and shear force parameters did not appear to have been affected by the coatings. In summary, as appearance is an important purchasing factor, the coating containing olive oil and pink pepper oil is very promising as an alternative for maintaining vacuum-packaged lamb meat quality.
RESUMO: Durante a vida de prateleira da carne fresca podem ocorrer mudanças físico-químicas, microbiológicas e sensoriais indesejadas. Para evitar tais mudanças a combinação da embalagem tradicional à vácuo com revestimentos comestíveis é uma alternativa. O objetivo deste estudo foi avaliar o efeito do uso de diferentes revestimentos comestíveis à base de zeínas em combinação com diferentes óleos vegetais (óleos de: pimenta rosa, alecrim, azeite e combinação de azeite + óleo de pimenta rosa ou alecrim) nas características fisico-químicas da carne ovina, embalada à vácuo e armazenada à temperatura 5±1 °C. Foram realizadas análises de pH, cor instrumental, capacidade de retenção de água (CRA), força de cisalhamento, substâncias reativas ao ácido tiobarbitúrico (TBARS) a cada sete dias, no período de 29 dias. Foram observadas diferenças significativas (P<0,05) para o efeito de revestimentos e o tempo de armazenamento. A combinação de azeite mais óleo de pimenta (OLPP), apresentou maior estabilidade de cor, enquanto que os revestimentos contendo alecrim (RO), alecrim mais azeite (OLRO) e óleo de pimenta (PP) foram os que apresentaram maior estabilidade oxidativa no período de 29 dias. Os parâmetros pH, CRA e força de cisalhamento não parecem ter sido afetados pelos revestimentos. Tendo em vista que aparência é um importante fator de compra, o revestimento contendo azeite e óleo de pimenta rosa foi o mais promissor para ser utilizado na manutenção da qualidade de carne ovina.
Summary
Pure zein films are known to be very hydrophobic, but are inappropriate for edible coating applications because of their brittle nature. In an attempt to improve the flexibility of these ...coatings, the influence of low concentrations of oleic acid (OA) as a plasticiser on mechanical, topographical and wetting properties of zein thin films was evaluated. Films were first obtained by casting from aqueous ethanol solutions with 4.0% in mass of zein and additions of 0%; 0.25%; 0.50%; and 1.0% (w/w) of OA. The results indicate an improvement in mechanical properties with increasing plasticiser leading to a reduction in the elastic modulus. An increase in the elongation at break has been observed, but with minor influence on tensile strength. All plasticised zein films have similar initial contact angle (approximately 69°) with a time‐dependent receding drop behaviour. An increase in plasticiser concentration increases film’s affinity towards water. As measured by atomic force microscopy, a consistent linear relation (R2 = 0.991) was estimated between film composition and surface adhesion and consequently on the hydrophilicity. Surface topography also varied with plasticiser addition, becoming smoother as the OA concentration increases. When tested as an edible coating on pears (Pyrus communis L.), a formulation with 0.25% wt of plasticiser achieved the best results in preserving the pear mass as measured during the evaluated storage time (12 days) at room temperature. A 0.5% concentration of plasticiser had no influence and higher amounts resulted in a reduction in fruit protection.
•13C CPMAS method was successfully used to quantify the crystallinity of chitosans;•The accuracy of 13C SSNMR is higher than conventional X-ray diffraction method;•13C SSNMR did not require amorphous ...standards to quantify the crystallinity of chitosans.
We propose a novel approach relied on high-resolution solid-state 13C NMR spectroscopy to quantify the crystallinity index of chitosans (Ch) prepared with variable average degrees of acetylation (DA¯) from 5% to 60 % and average weight molecular weight (M¯w) ranged in 0.15 × 106 g mol−1–1.2 × 106 g mol−1. The Dipolar Chemical Shift Correlation (DIPSHIFT) curve of the C(6)OH segment revealed increased mobility dynamic, which induced different distribution from trans-to-gauche conformations in relation to C(4). Indeed, 1H-13C Heteronuclear Correlation (2D HETCOR) showed that distinguished C4 chemical shifts correlates with the same aliphatic protons. The short-range ordering can be assigned to C4/C6 signals on 13C CPMAS and, for our case, the deconvolution procedure between disordered and ordered phases revealed increasing crystallinity with DA¯, as confirmed by SVD multivariate analysis. This work extended the knowledge regarding the use of 13C CPMAS technique to predict the crystallinity of chitosans without the use of amorphous standards.
Atomic Force Microscopy (AFM) can be used to obtain high-resolution topographical images of bacteria revealing surface details and cell integrity. During scanning however, the interactions between ...the AFM probe and the membrane results in distortion of the images. Such distortions or artifacts are the result of geometrical effects related to bacterial cell height, specimen curvature and the AFM probe geometry. The most common artifact in imaging is surface broadening, what can lead to errors in bacterial sizing. Several methods of correction have been proposed to compensate for these artifacts and in this study we describe a simple geometric model for the interaction between the tip (a pyramidal shaped AFM probe) and the bacterium (Escherichia coli JM-109 strain) to minimize the enlarging effect. Approaches to bacteria immobilization and examples of AFM images analysis are also described.
Mitochondrial dysfunction has been associated with the development of diabetes mellitus which is characterized by disorders of collagen production and impaired wound healing. This study analyzed the ...effects of photobiomodulation (PBM) mediated by laser and light-emitting diode (LED) on the production and organization of collagen fibers in an excisional wound in an animal model of diabetes, and the correlation with inflammation and mitochondrial dynamics.
Twenty Wistar rats were randomized into 4 groups of 5 animals. Groups: (SHAM) a control non-diabetic wounded group with no treatment; (DC) a diabetic wounded group with no treatment; (DLASER) a diabetic wounded group irradiated by 904 nm pulsed laser (40 mW, 9500 Hz, 1 min, 2.4 J); (DLED) a diabetic wounded group irradiated by continuous wave LED 850 nm (48 mW, 22 s, 1.0 J). Diabetes was induced by injection with streptozotocin (70 mg/kg). PBM was carried out daily for 5 days followed by sacrifice and tissue removal.
Collagen fibers in diabetic wounded skin were increased by DLASER but not by DLED. Both groups showed increased blood vessels by atomic force microscopy. Vascular endothelial growth factor (VEGF) was higher and cyclooxygenase (COX2) was lower in the DLED group. Mitochondrial fusion was higher and mitochondrial fusion was lower in DLED compared to DLASER.
Differences observed between DLASER and DLED may be due to the pulsed laser and CW LED, and to the higher dose of laser. Regulation of mitochondrial homeostasis may be an important mechanism for PBM effects in diabetes.
•LED activates anti-inflammatory COX 2 response more than laser.•Laser treatment had a better beneficial effect on collagen structure than LED.•There were differences between mechanisms of Photobiomodulation by Laser and LED.•Phototherapy regulated homeostatic balance between mitochondrial fusion and fission.•Immunohistochemistry analysis demonstrated increased VEGF in both irradiated groups.
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