Halophiles and Their Vast Potential in Biofuel Production

Global warming and the limitations of using fossil fuels are a main concern of all societies, and thus, the development of alternative fuel sources is crucial to improving the current global energy situation. Biofuels are known as the best alternatives of unrenewable fuels and justify increasing extensive research to develop new and less expensive methods for their production. The most frequent biofuels are bioethanol, biobutanol, biodiesel, and biogas. The production of these biofuels is the result of microbial activity on organic substrates like sugars, starch, oil crops, non-food biomasses, and agricultural and animal wastes. Several industrial production processes are carried out in the presence of high concentrations of NaCl and therefore, researchers have focused on halophiles for biofuel production. In this review, we focus on the role of halophilic microorganisms and their current utilization in the production of all types of biofuels. Also, the outstanding potential of them and their hydrolytic enzymes in the hydrolysis of different kind of biomasses and the production of biofuels are discussed

Fluid-structure interaction simulation of prosthetic aortic valves : comparison between immersed boundary and arbitrary Lagrangian-Eulerian techniques for the mesh representation

In recent years the role of FSI (fluid-structure interaction) simulations in the analysis of the fluid-mechanics of heart valves is becoming more and more important, being able to capture the interaction between the blood and both the surrounding biological tissues and the valve itself. When setting up an FSI simulation, several choices have to be made to select the most suitable approach for the case of interest: in particular, to simulate flexible leaflet cardiac valves, the type of discretization of the fluid domain is crucial, which can be described with an ALE (Arbitrary Lagrangian-Eulerian) or an Eulerian formulation. The majority of the reported 3D heart valve FSI simulations are performed with the Eulerian formulation, allowing for large deformations of the domains without compromising the quality of the fluid grid. Nevertheless, it is known that the ALE-FSI approach guarantees more accurate results at the interface between the solid and the fluid. The goal of this paper is to describe the same aortic valve model in the two cases, comparing the performances of an ALE-based FSI solution and an Eulerian-based FSI approach. After a first simplified 2D case, the aortic geometry was considered in a full 3D set-up. The model was kept as similar as possible in the two settings, to better compare the simulations' outcomes. Although for the 2D case the differences were unsubstantial, in our experience the performance of a full 3D ALE-FSI simulation was significantly limited by the technical problems and requirements inherent to the ALE formulation, mainly related to the mesh motion and deformation of the fluid domain. As a secondary outcome of this work, it is important to point out that the choice of the solver also influenced the reliability of the final results

Bioactive Inks Development for Osteochondral Tissue Engineering: A Mini-Review

Nowadays, a prevalent joint disease affecting both cartilage and subchondral bone is osteoarthritis. Osteochondral tissue, a complex tissue unit, exhibited limited self-renewal potential. Furthermore, its gradient properties, including mechanical property, bio-compositions, and cellular behaviors, present a challenge in repairing and regenerating damaged osteochondral tissues. Here, tissue engineering and translational medicine development using bioprinting technology provided a promising strategy for osteochondral tissue repair. In this regard, personalized stratified scaffolds, which play an influential role in osteochondral regeneration, can provide potential treatment options in early-stage osteoarthritis to delay or avoid the use of joint replacements. Accordingly, bioactive scaffolds with possible integration with surrounding tissue and controlling inflammatory responses have promising future tissue engineering perspectives. This minireview focuses on introducing biologically active inks for bioprinting the hierarchical scaffolds, containing growth factors and bioactive materials for 3D printing of regenerative osteochondral substitutes

Analytical solutions for single and multiple scattering from rib-stiffened plates in water

The interaction of an acoustic plane wave with a pair of plates connected by periodically spaced stiffeners in water is considered. The rib-stiffened structure is called a "flex-layer" because its low frequency response is dominated by bending stiffness. The quasi-static behavior is equivalent a homogeneous layer of compressible fluid, which we identify as air for the purposes of comparison. In this way an air layer is acoustically the same as a pair of thin elastic plates connected by a periodic spacing of ribs. At discrete higher frequencies the flex-layer exhibits perfect acoustic transmission, the cause of which is identified as fluid-loaded plate waves propagating back and forth between the ribs. Both the low and finite frequency behavior of the flex-layer are fully explained by closed-form solutions for reflection and transmission. The analytical model is extended to two flex-layers in series, introducing new low and high frequency phenomena that are explained in terms of simple lumped parameter models.Comment: 11 pages, 13 figure

Bioactive Inks Development for Osteochondral Tissue Engineering: A Mini-Review

Nowadays, a prevalent joint disease affecting both cartilage and subchondral bone is osteoarthritis. Osteochondral tissue, a complex tissue unit, exhibited limited self-renewal potential. Furthermore, its gradient properties, including mechanical property, bio-compositions, and cellular behaviors, present a challenge in repairing and regenerating damaged osteochondral tissues. Here, tissue engineering and translational medicine development using bioprinting technology provided a promising strategy for osteochondral tissue repair. In this regard, personalized stratified scaffolds, which play an influential role in osteochondral regeneration, can provide potential treatment options in early-stage osteoarthritis to delay or avoid the use of joint replacements. Accordingly, bioactive scaffolds with possible integration with surrounding tissue and controlling inflammatory responses have promising future tissue engineering perspectives. This minireview focuses on introducing biologically active inks for bioprinting the hierarchical scaffolds, containing growth factors and bioactive materials for 3D printing of regenerative osteochondral substitutes

Mechanistic Studies on Antibiotic Peptides: Lantibiotics and Lipopeptides

Antimicrobial peptides (AMPs) are small protein toxins produced by different bacterial strains to fight against closely related strains in their competitive environment. AMPs have been isolated and studied for their interesting properties, including treatment of pathogenic diseases. In this thesis, results of mechanistic studies on AMPs classified as lantibiotic and lipopeptide are discussed. In chapter 2, mechanistic studies on lacticin 3147 will be discussed. Lacticin 3147 is a two peptide lantibiotic (LtnA1 and LtnA2) that displays nanomolar activity against many Gram-positive bacteria. Lacticin 3147 may exert its antimicrobial effect by several mechanisms. Isothermal titration calorimetry experiments showed that only LtnA1 binds to the peptidoglycan precursor lipid II, which could inhibit peptidoglycan biosynthesis. An experimentally supported model of the resulting complex suggests the key binding partners are the C-terminus of LtnA1 and pyrophosphate of lipid II. A combination of in vivo and in vitro assays indicated that LtnA1 and LtnA2 can induce rapid membrane lysis without the need for lipid II binding. However, the presence of lipid II substantially increases the activity of lacticin 3147. Furthermore, studies with synthetic LtnA2 analogues containing either desmethyl- or oxa-lanthionine rings confirm that the precise geometry of these rings is essential for this synergistic activity. In chapter 3, mechanistic studies on tridecaptin A1 (TriA1) and the synthesis of its analogues will be discussed. Tridecaptin A1 belongs to the lipopeptide class of AMPs with selective activity against Gram-negative bacteria. Our studies showed that TriA1 exerts its bactericidal effect by interacting with bacterial cell wall precursor lipid ll to interrupt the proton motive force