Improved reliability and mechanical performance of Sn58Bi solder alloys

Microstructural and mechanical properties of the eutectic Sn58Bi and micro-alloyed Sn57.6Bi0.4Ag solder alloys were compared. With the addition of Ag micro-alloy, the tensile strength was improved and this is attributed to a combination of microstructure refinement and an Ag3Sn precipitation hardening mechanism. However, ductility is slightly deteriorated due to the brittle nature of the Ag3Sn intermetallic compounds (IMCs). Additionally, a board level reliability study of Ag micro-alloyed Sn58Bi solder joints produced utilising a surface-mount technology (SMT) process, were assessed under accelerated temperature cycling (ATC) conditions. Results reveal that micro-alloyed Sn57.6Bi0.4Ag has a higher characteristic lifetime with a narrower failure distribution. This enhanced reliability corresponds with improved bulk mechanical properties. It is postulated that Ag3Sn IMCs are located at the Sn-Bi phase boundaries and suppress the solder microstructure from coarsening during the temperature cycling, hereby extending the time to failure

Synthesis and evaluation of alginate, gelatin, and hyaluronic acid hybrid hydrogels for tissue engineering applications

Tissue engineering (TE) has been proposed extensively as a potential solution to the worldwide shortages of donor organs needed for transplantation. Over the years, numerous hydrogel formulations have been studied for various TE endeavours, including bone, cardiac or neural TE treatment strategies. Amongst the materials used, organic and biocompatible materials which aim to mimic the natural extracellular matrix of the native tissue have been investigated to create biomimicry regenerative environments. As such, the comparison between studies using the same materials is often difficult to accomplish due to varying material concentrations, preparation strategies, and laboratory settings, and as such these variables have a huge impact on the physio-chemical properties of the hydrogel systems. The purpose of the current study is to investigate popular biomaterials such as alginate, hyaluronic acid and gelatin in a variety of concentrations and hydrogel formulations. This aims to provide a clear and comprehensive understanding of their behaviours and provide a rational approach as to the appropriate selection of natural polysaccharides in specific targeted TE strategies.</p

Efficient production of 5-ethoxymethylfurfural from 5-hydroxymethylfurfural and carbohydrates over lewis/brønsted hybrid magnetic dendritic fibrous silica core-shell catalyst

In the present work, a series of Brønsted and Lewis hybrid, magnetic, dendritic fibrous silica microsphere core shell particles with an open and easily accessible mesopore channels as the catalyst supports (Fe3O4@SiO2@KCC-1) were prepared, impregnated with aluminum (10 wt%) followed by encapsulation of different loadings of tungstophosphoric acid (PTA) from 10 to 40 wt% into mesoporous channels of fibrous silica shell (Fe3O4@SiO2@KCC-1/Al10/PTAx). They are utilised for the efficient and clean production of biomass-derived liquid fuel 5-ethoxymethylfurfural (EMF) through direct etherification of hydroxymethylfurfural (HMF) and one-pot conversion of fructose and other carbohydrates. High EMF yields of 93.1%, 62.2%, 23.9%, and 21.4% were obtained, when HMF, fructose, sorbose, and sucrose were subjected as substrate, respectively. These catalysts were characterised by XRD, py-FTIR, TGA, N2-physisorption, SEM and TEM-EDX mapping. Importantly, the catalyst could be reused at least four times almost without a significant loss of activity

Hyaluronic acid association with bacterial, fungal and viral infections: Can hyaluronic acid be used as an antimicrobial polymer for biomedical and pharmaceutical applications?

The relationships between hyaluronic acid (HA) and pathological microorganisms incite new understandings on microbial infection, tissue penetration, disease progression and lastly, potential treatments. These understandings are important for the advancement of next generation antimicrobial therapeutical strategies for the  control of healthcare-associated infections. Herein, this review will focus on the interplay between HA, bacteria, fungi, and viruses. This review will also comprehensively detail and discuss the antimicrobial activity displayed  by various HA molecular weights for a variety of biomedical and pharmaceutical applications, including  microbiology, pharmaceutics, and tissue engineering.  </p

Recent progress in biomedical and biotechnological applications of lignin-based spherical nano- and microstructures: a comprehensive review

Spherical particles based on materials of natural origin have recently gained increased attention because of their unique properties, including shape, structure, and ability to combine with other materials. Lignin has potential to be applied across multiple sectors, with recent focus on its valorization in high end application routes which favor its renewability, biocompatibility, and non-toxicity. The most promising findings are reported, that spherical lignin particles are a very effective carrier and delivery vehicle for active pharmaceutical ingredients for the treatment of various diseases, including cancers etc. Due to recent developments, lignin can be successfully used for accelerated wound healing and for growth inhibition against a variety of bacterial strains taking advantage of its inherent antimicrobial and anti-oxidant properties. Notably, lignin particles are also finding opportunities in the agrochemical industry, taking advantage of a combination of properties such as high stability, composability, and the possibility of encapsulation of pesticides and fungicides without increased pollution of the environment. The presented review aims to discuss the impact of recent developments related to lignin-based spherical particles on novel biomedical and biotechnological application, which may provide guidance for future possibilities for the valorization of lignin </p

Facile tailoring of structures for controlled release of paracetamol from sustainable lignin derived platforms

Nowadays, sustainable materials are receiving significant attention due to the fact that they will be crucial for the development of the next generation of products and devices. In the present work, hydrogels have been successfully synthesized using lignin which is non-valorized biopolymer from the paper industry. Hydrogels were prepared via crosslinking with Poly(ethylene) glycol diglycidyl ether (PEGDGE). Different crosslinker ratios were used to determine their influence on the structural and chemical properties of the resulting hydrogels. It has been found that pore size was reduced by increasing crosslinker amount. The greater crosslinking density increased the swelling capacity of the hydrogels due to the presence of more hydrophilic groups in the hydrogel network. Paracetamol release test showed higher drug diffusion for hydrogels produced with a ratio lignin:PEGDGE 1:1. The obtained results demonstrate that the proposed approach is a promising route to utilize lignocellulose waste for producing porous materials for advanced biomedical applications in the pharmacy industry

Thermoelectric properties of electrospun carbon nanofibres derived from lignin

Developing sustainable and efficient thermoelectric materials is a challenge because the most common thermoelectric materials are based on rare elements such as bismuth and telluride. In this context, we have produced bio-based carbon nanofibres (CNFs) derived from mixtures of polyacrylonitrile and lignin using electrospinning. The addition of lignin (up to 70%) reduces the diameter of CNFs from 450 nm to 250 nm, increases sample flexibility, and promotes inter-fibre fusion. The crystalline structure of the CNFs was analysed by Raman spectroscopy. The electrical conductivity and the Seebeck coefficient were evaluated as function of the lignin content in the precursor and carbonised equivalents. Finally, a conversion of p-type to n-type semiconducting behaviour was achieved with a hydrazine vapour treatment. We observe a maximum p-type power factor of 9.27 μW cm-1 K-2 for CNFs carbonised at 900°C with 70% lignin which is a 34.5-fold increase to the CNFs with 0% lignin. For the hydrazine treated samples, we observe a maximum n-type power factor of 10.2 μW cm-1 K-2 for the CNFs produced in the same way which is an 11.0-fold increase to the hydrazine-treated CNFs with 0% lignin

Biomaterials: Antimicrobial surfaces in biomedical engineering and healthcare

Contamination of biomedical products with pathogenic microorganisms (bacteria, fungi, and viruses) is one of the main causes of hospital-acquired infections (HAI), and a major burden to the healthcare system. The development of biomaterials that can hamper the contamination of surfaces is vital to decrease patient-related infections in healthcare settings. In this landscape, this review identifies some of the latest antimicrobial strategies while paying particular attention to emerging antimicrobial biomaterials and nature-inspired antimicrobial surface topographies, which are rapidly finding application in the fabrication of biomedical engineering constructs.</p

Cellulose: Characteristics and applications for rechargeable batteries

Cellulose, an abundant natural polymer, has promising potential to be used for energy storage systems because of its excellent mechanical, structural, and physical characteristics. This review discusses the structural features of cellulose and describes its potential application as an electrode, separator, and binder, in various types of high-performing batteries. Various surface and structural characteristics of cellulose (e.g., fiber size, surface functional groups, the hierarchy of pores, and porosity levels) that contribute to its electrochemical performance are discussed. Cellulose structure/property/processing/function relationships are further focused and elucidated in terms of the latest developments in the emerging field of sustainable materials in Li-Ion, Na-Ion, and Li–S batteries. </p

The impact of varying dextran oxidation levels on the inhibitory activity of a bacteriocin loaded injectable hydrogel

In the design of injectable antimicrobial dextran-alginate hydrogels, the impact of dextran oxidation and its subsequent  changes in molecular weight and the incorporation of glycol chitosan on (i) gel mechanical strength and (ii) the inhibitory profle of an encapsulated bacteriocin, nisin A, are explored. As the degree of oxidation increases, the weight average  molecular mass of the dextran decreases, resulting in a reduction in elastic modulus of the gels made. Upon encapsulation  of the bacteriocin nisin into the gels, varying the dextran mass/oxidation level allowed the antimicrobial activity against  S. aureus to be controlled. Gels made with a higher molecular weight (less oxidised) dextran show a higher initial degree  of inhibition while those made with a lower molecular weight (more oxidised) dextran exhibit a more sustained inhibition.  Incorporating glycol chitosan into gels composed of dextran with higher masses signifcantly increased their storage modulus  and the gels’ initial degree of inhibition. </p