Performance prediction of PM 2.5 removal of real fibrous filters with a novel model considering rebound effect

Fibrous filters have been proved to be one of the most cost-effective way of particulate matters (specifically PM 2.5) purification. However, due to the complex structure of real fibrous filters, it is difficult to accurately predict the performance of PM2.5 removal. In this study, a new 3D filtration modeling approach is proposed to predict the removal efficiencies of particles by real fibrous filters, by taking the particle rebound effect into consideration. A real filter is considered and its SEM image-based 3D structure is established for modeling. Then based on the simulation result, the filtration efficiency and pressure drop are calculated. The obtained values are compared and validated by experimental data and empirical correlations, and the results are proven to be in good agreement with each other. At last, influences of various parameters including the face velocity, particle size and the particle rebound effect on the filtration performance of fibrous filters are investigated. The results provide useful guidelines for the optimization and enhancement of PM2.5 removal by fibrous filter

Fabrication and characterisation of electrospun silk fibroin/gelatin scaffolds crosslinked with glutaraldehyde vapour

Bombyx mori silk fibroin (SF) /gelatin nanofibre mats with different blend ratios of 100/0, 90/10 and 70/30 were prepared by electrospinning and crosslinked with glutaraldehyde (GTA) vapour at room temperature. GTA was shown to induce the conformational transition of SFs from random coils to β-sheets along with increasing nanofibre diameters with the addition of gelatin into SFs. It was found that by increasing the gelatin content, crosslinking degree was enhanced from 34% for pure SF nanofibre mats to 43% for SF/gelatin counterparts at the blend ratio of 70/30, which directly affected mechanical properties, porosity, and water uptake capacity (WUC) of prepared nanofibre mats. The addition of 10 and 30 wt% gelatin into SFs improved tensile strengths of SF/gelatin nanofibre mats by 10 and 27% along with significant increases in Young’s modulus by 1.1 and 1.3 times, respectively, as opposed to plain SF counterparts. However, both porosity and WUC were found to decrease from 62 and 405% for pristine SF nanofibre mats to 47% and 232% for SF/gelatin counterparts at the blend ratio of 70/30 accordingly. To further evaluate the combined effect of GTA crosslinking and gelatin content on biological response of SF/gelatin scaffolds, the proliferation assay using 3T3 mouse fibroblast was conducted. In comparison with pure SFs, cell proliferation rate was lower for SF/gelatin constructs, which declined when the gelatin content increased. These results indicated that the adverse effect of GTA crosslinking on cell response may be ascribed to imposed changes in morphology and physiochemical properties of SF/gelatin nanofibre mats. Although crosslinking could be used to improve mechanical properties of nanofibre mats, it reduced their capacity to support the cell activity. GTA optimisation is required to further modulate the physico-chemical properties of SF/gelatin nanofibre mats in order to obtain stable materials with favourable bioactive properties and promote cellular responses for tissue engineering applications

Electroactive smart materials: novel tools for tailoring bacteria behavior and fight antimicrobial resistance

Despite being very simple organisms, bacteria possess an outstanding ability to adapt to different environments. Their long evolutionary history, being exposed to vastly different physicochemical surroundings, allowed them to detect and respond to a wide range of signals including biochemical, mechanical, electrical, and magnetic ones. Taking into consideration their adapting mechanisms, it is expected that novel materials able to provide bacteria with specific stimuli in a biomimetic context may tailor their behavior and make them suitable for specific applications in terms of anti-microbial and pro-microbial approaches. This review maintains that electroactive smart materials will be a future approach to be explored in microbiology to obtain novel strategies for fighting the emergence of live threatening antibiotic resistance.This work was supported by national funds through FCT (Fundação para a Ciência e Tecnologia) and by ERDF through COMPETE2020—Programa Operacional Competitividade e Internacionalização (POCI) in the framework of the Strategic Programs UID/FIS/04650/2019. This work was also supported by FCT through project LungChek ENMed/0049/2016. MF and EC thank FCT for the SFRH/BPD/121464/2016 and SFRH/BD/145455/2019 grant, respectively. Finally, the authors acknowledge funding by the Spanish Ministry of Economy and Competitiveness (MINECO) through the project MAT201676039-C4-3-R (AEI/FEDER, UE) and from the Basque Government Industry and Education Departments under the ELKARTEK and PIBA (PIBA-2018-06) programs, respectively.info:eu-repo/semantics/publishedVersio

Instructive conductive 3D silk foam-based bone tissue scaffolds enable electrical stimulation of stem cells for enhanced osteogenic differentiation

Stimuli-responsive materials enabling the behaviour of the cells that reside within them to be controlled are vital for the development of instructive tissue scaffolds for tissue engineering. Herein we describe the preparation of conductive silk foam-based bone tissue scaffolds that enable the electrical stimulation of human mesenchymal stem cells to enhance their differentiation towards osteogenic outcomes

Porous magnesium-based scaffolds for tissue engineering.

Significant amount of research efforts have been dedicated to the development of scaffolds for tissue engineering. Although at present most of the studies are focused on non-load bearing scaffolds, many scaffolds have also been investigated for hard tissue repair. In particular, metallic scaffolds are being studied for hard tissue engineering due to their suitable mechanical properties. Several biocompatible metallic materials such as stainless steels, cobalt alloys, titanium alloys, tantalum, nitinol and magnesium alloys have been commonly employed as implants in orthopedic and dental treatments. They are often used to replace and regenerate the damaged bones or to provide structural support for healing bone defects. Among the common metallic biomaterials, magnesium (Mg) and a number of its alloys are effective because of their mechanical properties close to those of human bone, their natural ionic content that may have important functional roles in physiological systems, and their in vivo biodegradation characteristics in body fluids. Due to such collective properties, Mg based alloys can be employed as biocompatible, bioactive, and biodegradable scaffolds for load-bearing applications. Recently, porous Mg and Mg alloys have been specially suggested as metallic scaffolds for bone tissue engineering. With further optimization of the fabrication techniques, porous Mg is expected to make a promising hard substitute scaffold. The present review covers research conducted on the fabrication techniques, surface modifications, properties and biological characteristics of Mg alloys based scaffolds. Furthermore, the potential applications, challenges and future trends of such degradable metallic scaffolds are discussed in detail