Bionanomaterials from plant viruses

Plant virus capsids have emerged as useful biotemplates for material synthesis. All plant virus capsids are assembled with high-precision, three-dimensional structures providing nanoscale architectures that are highly monodisperse, can be produced in large quantities and that cannot replicate in mammalian cells (so are safe). Such exceptional characteristics make plant viruses strong candidates for application as biotemplates for novel and new material synthesis

Templated mineralization by charge-modified cowpea mosaic virus

Templated mineralization of virus particles provides routes to narrowly dispersed nanoparticles that are not readily prepared by other means. The templated mineralization of metal or metal oxide on the external surface of wild-type cowpea mosaic virus (CPMV), a plant virus, is facilitated by increasing the external surface negative charge. This is achieved by the chemical modification of surface lysine groups by succinic anhydride. Hence, for example, treatment of charge-modified CPMV succinamate with a 1:2 mixture of iron(II) and iron(III) salts, followed by raising the pH to 10.2, led to the formation of narrowly dispersed, CPMV-templated, magnetite (Fe3O4) nanoparticles

Polyelectrolyte-modified cowpea mosaic virus for the synthesis of gold nanoparticles

Polyelectrolyte surface-modified cowpea mosaic virus (CPMV) can be used for the templated synthesis of narrowly dispersed gold nanoparticles. Cationic polyelectrolyte, poly(allylamine) hydrochloride, is electrostatically bound to the external surface of the virus capsid. The polyelectrolyte-coated CPMV promotes adsorption of aqueous gold hydroxide anionic species, prepared from gold(III) chloride and potassium carbonate, that are easily reduced to form CPMV-templated gold nanoparticles. The process is simple and environmentally benign using only water as solvent at ambient temperature

Nonlinear acoustic wave propagation with diffusion and relaxation

A sonic boom is the sound associated with the pressure shock wave generated by disturbances in the atmosphere that lead to rapid increases in pressure over a short time. This research considers the propagation of the finite-amplitude plane waveform involving a balance of nonlinear steepening and other physical dissipation mechanisms. These dissipation mechanisms include the effect of viscosity and molecular relaxation associated with the vibration of polyatomic molecules. When the shock is controlled solely by thermoviscous diffusion the disturbance is governed by Burgers’ equation. A comprehensive study is undertaken with the emphasis on shock position, amplitude and thickness. This study is concerned with the applications of the combined approaches of matched asymptotic expansions, Cole-Hopf transformation, the method of characteristics, and numerical schemes such as Fourier pseudo-spectral method and the fourth-order Runge-Kutta method. The augmented Burgers’ equation is used when thermoviscosity and relaxation processes are taken into account. An asymptotic analysis of the shock profile is conducted governing the cases of one and two relaxation modes. This analysis reached a descriptive classification of the shock structure based upon the variations in relaxation parameters. The numerical schemes are adopted to simulate the propagation through the relaxing medium, and comparisons are made with the asymptotic findings. Asymptotic predications of the shock thickness, which is controlled by various physical mechanisms, are presented and compared with numerical results

Asymptotic and numerical analysis of pulse propagation in relaxation media

We consider the case of disturbances propagating in one-dimension through a medium with multiple relaxation modes and thermoviscous diffusion. Each relaxation mode is characterized by two parameters and the evolution of the disturbance is governed by an augmented Burgers equation. We begin by considering travelling wave solutions for the propagation of a pressure step, of amplitude P, in the small viscosity limit. For a single relaxation mode, if the amplitude P is less than a certain critical value then the transition is controlled entirely by the relaxation mode whereas for larger P, a thin viscous sub-shock arises. We then consider the propagation of a rectangular pulse. We establish parameter ranges in which the waveform is described by an outer solution (obtained using characteristics) and a thin shock region. Analysis of the shock region then reveals the same richness of structure seen in the travelling wave case, with subtle changes in shock structure as the disturbance decays. This is illustrated by numerical results using a pseudospectral method. Finally, analysis of the case of two relaxation modes is presented demonstrating that in some parameter regimes the transition region consists of three separate sub-regions governed by the three different physical processes

Alginate: Enhancement Strategies for Advanced Applications

Alginate is an excellent biodegradable and renewable material that is already used for a broad range of industrial applications, including advanced fields, such as biomedicine and bioengineering, due to its excellent biodegradable and biocompatible properties. This biopolymer can be produced from brown algae or a microorganism culture. This review presents the principles, chemical structures, gelation properties, chemical interactions, production, sterilization, purification, types, and alginate-based hydrogels developed so far. We present all of the advanced strategies used to remarkably enhance this biopolymer’s physicochemical and biological characteristics in various forms, such as injectable gels, fibers, films, hydrogels, and scaffolds. Thus, we present here all of the material engineering enhancement approaches achieved so far in this biopolymer in terms of mechanical reinforcement, thermal and electrical performance, wettability, water sorption and diffusion, antimicrobial activity, in vivo and in vitro biological behavior, including toxicity, cell adhesion, proliferation, and differentiation, immunological response, biodegradation, porosity, and its use as scaffolds for tissue engineering applications. These improvements to overcome the drawbacks of the alginate biopolymer could exponentially increase the significant number of alginate applications that go from the paper industry to the bioprinting of organs

Prepectoral Versus Subpectoral Direct-to-Implant-Based Breast Reconstruction: A Meta-Analysis of 3851 patients

Introduction: The subpectoral direct-to-implant (SP-DTI) surgical technique is the standard and most common for breast reconstruction which could reduce implant visibility and palpability, and it manipulates the pectoralis major muscle with some post-operative complications such as muscle spasm, animation deformities, and pain while the prepectoral direct-to-implant (PP-DTI) approach leaves the muscle intact. Therefore, we conducted this meta-analysis to assess the efficacy and safety of the PP-DTI procedure after mastectomies compared to the standard breast reconstruction.   Methods: We performed a comprehensive search for the following databases: PubMed, Cochrane (Medline), Web of Science, and Scopus. All studies published in English till February 2022 were included. These include randomized and non-randomized clinical trials comparing Operation Time, Duration of Hospitalization (DOH), Breast Animation Deformity (BAD), Implant loss, Wound infection and dehiscence, seroma as well as post-operative pain. The study’s quality will be assessed according to the Cochrane risk-of-bias tool for randomized trials (RoB2) and the ROBINS-I risk of bias tool to assess non-randomized studies of interventions.   Results: There were 28 comparative studies including 3851 patients carried out breast reconstruction surgeries. Post-operative complications were comparable between the two groups as follows: implant loss (OR 1.17, 95% CI [0.71-1.94]), wound dehiscence (OR 0.76, 95% CI [0.43-1.32]), wound infection (OR 1.09, 95% CI [0.78-1.53]), and seroma (OR 0.78, 95% CI [0.56-1.09]). The PP-DTI group was significantly less likely to develop BAD compared to SP-DTI group (OR 0.02, 95% CI [0.00-0.12]). Patients undergoing PP-DTI reconstruction had significantly reduced postoperative pain (SMD -0.55, 95% CI [-0.78 - -0.32]). Operation time and DOH were significantly lower among PP-DTI group ((SMD -0.35, 95% CI [-0.61 - -0.08]), (SMD -0.89, 95% CI [-1.48 - -0.30], respectively)).   Conclusion Following mastectomy, PP-DTI breast reconstruction significantly reduced post-operative pain, BAD, DOH, intra-operative time compared with SP-DTI reconstruction, although there was no significant difference in complication rate. A PP-DTI is a simple and safe alternative to the subpectoral technique allowing early discharge and improving patient's quality of life. Future well-designed multicenter randomized controlled trials that compare two approaches and discuss the cost-effectiveness are needed.   Keywords: PP-DTI, SP-DTI, Meta-analysis, cosmetics. &nbsp