Harnessing diurnal dynamics: Deciphering the interplay of light cycles on algal-bacterial membrane bioreactors

Light profoundly modulates the algal-bacterial membrane bioreactor (algal-bacterial MBR) performance. Yet, its outdoor deployment grapples with the inherent diurnal cycle of sunlight, engendering suboptimal light conditions. The adaptability of such systems to these fluctuating light conditions and their implications for practical outdoor applications remained an under-explored frontier. In response, this study meticulously scrutinized two laboratory-scale algal-bacterial MBRs under varying light regimes: a 24-h continuous and a 12-h cyclic illumination. Over 70 days, continuous illumination was observed to yield superior biomass production and total nitrogen and total phosphorus removal efficiencies compared to its cyclic counterpart. Contrarily, when focusing on membrane fouling, the 12-h cyclic illumination exhibited lower membrane fouling. The spectral analyses coupled with adhesion ability evaluation, traced the enhanced membrane fouling under continuous illumination to the elevated organics and heightened adhesive properties of the flocs. Given the tangible benefits of reduced membrane fouling and the potential harnessing of solar radiation, the 12-h cyclic illumination emerges as an economically astute operational paradigm for algal-bacterial MBRs. The significance of this study is to promote the application of algal-bacterial MBR in sewage treatment and provide robust support for the development of green technology in the future.

An introduction of biological performance of zirconia with different surface characteristics: A review

Zirconia (ZrO₂) ceramic is widely used in dentistry as a clinical dental biomaterial. In this review, we are focusing on and summarizing the biological performance of zirconia under different surface characteristics. We have included an initial tissue cell attachment study on zirconia and bacterial adhesion on zirconia. Our results suggest that surface modifications applied on zirconia may change the interfacial surface characteristics e.g. surface roughness, surface free energy, and chemistry of zirconia. The modifications also result in advanced biological performance of zirconia, including enhanced tissue cell attachment and reduction of bacterial adhesion. The recent laboratory research has provided many interesting modification methods and showed clinically interesting and promising outcomes. A few of the outcomes are validated and have been applied in clinical dentistry.

Bio-based Preservative using Methyl-β-cyclodextrin-Essential Oil Complexes for Wood Protection

Developing natural preservatives for wood protection is of great interest in sustainable construction and green building industries. This study was designed to determine the feasibility of using methyl-β-cyclodextrin-essential oils (MβCD-EOs) complexes as potential bio-based preservatives for wood protection. Four essential oils (EOs) with proven antifungal properties, eugenol (EG), trans-cinnamaldehyde (CN), thymol (TM) and carvacrol (CV), were complexed with methyl-β-cyclodextrin (MβCD) by a co-precipitation method. The inclusion of EOs in MβCD and the corresponding inclusion yield of the MβCD-EOs complexes were determined by attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) and ultraviolet-visible spectroscopy (UV/Vis), respectively. The maximum inclusion yields in MβCD-EG, MβCD-CN, MβCD-CV, and MβCD-TM were estimated to be almost 100%. MβCD-EOs complexes were impregnated into southern pine wood blocks and exposed to two brown rot fungi, Gloeophyllum trabeum and Postia placenta, following procedures described in AWPA Standard E22 and E10. The penetration of MβCD-EOs complexes in wood was confirmed by fluorescence microscopic analysis after the selective dyeing of EOs encapsulated in MβCD. In comparison to the control wood samples, MβCD-EOs complexes treated wood exhibited a significant reduction in the mass loss from 16-36% to 2-18%, accompanied by improvement in radial compression strength loss from 81-92% to 29-67% after four-week fungi exposure.

Bioactive glass (45S5)-based 3D scaffolds coated with magnesium and zinc-loaded hydroxyapatite nanoparticles for tissue engineering applications

Bioactive glass (BG)-based scaffolds of 45S5 composition covered with hydroxyapatite nanoparticles loaded with Mg²⁺, Zn²⁺ and, both Mg²⁺ and Zn²⁺ ions, were developed and tested as materials for tissue engineering applications. The scaffolds were prepared by the foam replica technique and mono- and bi-metal loaded and unloaded hydroxyapatite nanoparticles (HA, Zn-HA, Mg-HA and Mg-Zn-HA) were obtained by an adaptation of the wet chemical deposition method. Coating of BG with these nanoparticles was performed by dip-coating to obtain HA-BG, Zn-HA-BG, Mg-HA-BG and Mg-Zn-HA-BG scaffolds. As predictor of the bone bonding ability of the produced scaffolds, in this study we investigated the formation of an apatite layer on the scaffold surfaces in the presence of simulated body fluid. The cytotoxicity and osteogenic properties of the materials in vitro was evaluated using human osteoblast-like MG-63 cell cultures. The mineralization assay following Kokubo's protocol indicated that bi-metal loaded Mg-Zn-HA-BG scaffolds exhibited higher/faster bioactivity than mono-metal loaded scaffolds while mineralization of HA-BG, Zn-HA-BG and Mg-HA-BG was similar to that of uncoated scaffolds. Moreover, an increase of proliferation of MG-63 cells after 48 h and 7 days was measured by BrdU assays for Mg-Zn-HA-BG scaffolds. In agreement with these results, SEM images confirmed increased interaction between these scaffolds and cells, in comparison to that observed for mono-metal-loaded HA-coated scaffolds. Altogether, the obtained results suggest that nanocrystalline Mg-Zn-HA coatings enhance the biological performance of standard scaffolds of 45S5 BG composition. Thus these novel ion doped HA coated scaffolds are attractive systems for bone tissue engineering.

Preparation, bioactivity and mechanism of nano-hydroxyapatite/sodium alginate/chitosan bone repair material

BACKGROUND

As the major inorganic component of natural bone, nano-hydroxyapatite (n-HA) on its own is limited in its use in bone repair, due to its brittleness. Chitosan (CS) and sodium alginate (SAL) are used to reduce its brittleness and tendency to degradation. However, the compressive strength of the composite is still low, and its biological performance needs further study.

METHODS

Nano-hydroxyapatite/sodium alginate/chitosan (n-HA/SAL/CS) composite was prepared via an in situ synthesis method. Further, we prepared the n-HA/SAL/CS self-setting bone repair material by mixing n-HA/SAL/CS powder with a curing liquid (20 wt.% citric acid). In addition, the in vitro bioactivity and cell cytotoxicity were also explored.

RESULTS

Transmission electron microscopy photos revealed that the n-HA crystals were uniformly distributed throughout the polymer matrix. Infrared IR spectroscopy indicated that the HA interacted with the COO^- of SAL and NH₂^- of CS. The compressive strength of the n-HA/SAL/CS bone cement was 34.3 MPa and matched the demands of weight-bearing bones. Soaking in vitro in simulated body fluid demonstrated that the composite material had reasonably good bioactivity, while cytotoxicity tests indicated that the n-HA/SAL/CS cement could promote cell proliferation and was biocompatible.

CONCLUSIONS

Compressive strength of n-HA/SAL/CS can satisfy the needs of cancellous bone, and in vitro bioactivity and cytotoxicity tests results indicated that the n-HA/SAL/CS composite could act as an optimal bone repair material.

The physicochemical/biological properties of porous tantalum and the potential surface modification techniques to improve its clinical application in dental implantology

More rapid restoration and more rigid functionality have been pursued for decades in the field of dental implantology. Under such motivation, porous tantalum has been recently introduced to design a novel type of dental implant. Porous tantalum bears interconnected porous structure with pore size ranging from 300 to 600μm and a porosity of 75-85%. Its elastic modulus (1.3-10GPa) more closely approximates that of natural cortical (12-18GPa) and cancellous bone (0.1-0.5GPa) in comparison with the most commonly used dental materials, such as titanium and titanium alloy (106-115GPa). Porous tantalum is highly corrosion-resistant and biocompatible. It can significantly enhance the proliferation and differentiation of primary osteoblasts derived from elderly people than titanium. Porous tantalum can allow bone ingrowth and establish not only osseointegration but also osseoincorporation, which will significantly enhance the secondary stability of implants in bone tissue. In this review, we summarize the physicochemical, mechanical and biological properties of porous tantalum. We further discuss the performance of current tantalum dental implants and present the methodologies of surface modifications in order to improve their biological performance.