Nanomaterials synthesis by a novel phenomenon: The nanoscale Rayleigh-Taylor instability

The Rayleigh-Taylor (RT) interfacial instability has been attributed to physical phenomenon in a wide variety of macroscopic systems, including black holes, laser generated plasmas, and thick fluids. However, evidence for its existence in the nanoscale is lacking. Here we first show theoretically that this instability can occur in films with thickness negligible compared to the capillary length when they are heated rapidly inside a bulk fluid. Pressure gradients developed in the evaporated fluid region produce large forces causing the instability. Experiments were performed by melting Au films inside glycerol fluid by nanosecond laser pulses. The ensuingnanoparticles had highly monomodal size distributions. Importantly, the spacing of thenanoparticles was independent of the film thickness and could be tuned by the magnitude of the pressure gradients. Therefore, this instability can overcome some of the limitations of conventional thin self-organization techniques that rely on film thickness to control length scales

Nanomaterials synthesis by a novel phenomenon: The nanoscale Rayleigh-Taylor instability

The Rayleigh-Taylor (RT) interfacial instability has been attributed to physical phenomenon in a wide variety of macroscopic systems, including black holes, laser generated plasmas, and thick fluids. However, evidence for its existence in the nanoscale is lacking. Here we first show theoretically that this instability can occur in films with thickness negligible compared to the capillary length when they are heated rapidly inside a bulk fluid. Pressure gradients developed in the evaporated fluid region produce large forces causing the instability. Experiments were performed by melting Au films inside glycerol fluid by nanosecond laser pulses. The ensuing nanoparticles had highly monomodal size distributions. Importantly, the spacing of the nanoparticles was independent of the film thickness and could be tuned by the magnitude of the pressure gradients. Therefore, this instability can overcome some of the limitations of conventional thin self-organization techniques that rely on film thickness to control length scales

Controlling Nanoparticles Formation in Molten Metallic Bilayers by Pulsed-Laser Interference Heating

The impacts of the two-beam interference heating on the number of core-shell and embedded nanoparticles and on nanostructure coarsening are studied numerically based on the non-linear dynamical model for dewetting of the pulsed-laser irradiated, thin (< 20 nm) metallic bilayers. The model incorporates thermocapillary forces and disjoining pressures, and assumes dewetting from the optically transparent substrate atop of the reflective support layer, which results in the complicated dependence of light reflectivity and absorption on the thicknesses of the layers. Stabilizing thermocapillary effect is due to the local thickness-dependent, steady-state temperature profile in the liquid, which is derived based on the mean substrate temperature estimated from the elaborate thermal model of transient heating and melting/freezing. Linear stability analysis of the model equations set for Ag/Co bilayer predicts the dewetting length scales in the qualitative agreement with experiment

Scalable Synthesis of Janus Particles with High Naturality

Because of the increasing concerns about the ecological damage and negative health effects that may be caused by petrochemical-based microbeads, many countries are banning their use in a wide range of consumer products. One particular class of particles that may never reach their full potential because of such a ban is Janus particles, which are particles with two opposite properties. Despite significant progress in the scalable synthesis of Janus particles, most studies rely on petrochemical-based materials and solvents to enable their synthesis. In this report, we present a single-emulsion polymerization method for scalable synthesis of amphiphilic Janus particles with materials derived from plants. Soybean oil-epoxidized acrylate (SBOEA) monomers are polymerized in single-emulsion droplets of SBOEA, ethyl cellulose (EC), butyl acetate, and initiators that can be generated by either bulk or microfluidic emulsification, leading to the formation of amphiphilic soybean oil polymer/EC (SBOP/EC) Janus particles. Interfacial anchoring of the in situ-formed SBOP particles at the interface of the emulsion droplet plays a key role in the formation of the SBOP/EC Janus particles. Large-scale preparation of uniform SBOP/EC Janus particles is also demonstrated using a glass-silicon microfluidic device. Finally, the SBOP/EC Janus particles show potential to stabilize oil-in-water emulsions that can stay stable under flowing conditions

Randomised trial of two embolic agents for uterine artery embolisation for fibroids: Gelfoam versus Embospheres (RAGE trial)

Abstract Background Uterine artery embolisation (UAE) is an established treatment option for women with symptomatic uterine fibroids who wish to avoid surgery. However the most efficacious embolic agent remains uncertain. Methods We conducted a pilot double blind randomized controlled trial comparing Gelfoam with Embospheres in women undergoing UAE. Outcomes recorded at baseline, 24-h, 1 and 6 months included complications, inflammatory, haematological markers and ovarian function. Contrast enhanced MRI (CEMRI) was acquired at baseline, 24-h and 6 months. Pain score (visual analogue) was measured at 24-h, quality of life (UFS-Qol) at baseline, 1 and 6 months. All patients were followed to 6 months. Results Twenty patients were randomized 1:1 to receive either Gelfoam (G) or Embospheres (E). The UFS-Qol symptom score improved in both groups at 6 months mean of 64 ± 18 to 23 ± 16 and 54 ± 15 to 32 ± 26 in the E and G groups respectively. UFS-Qol HRQL also improved in both groups at 6 months, mean 41 ± 28 to 79 ± 20 and 53 ± 19 to 78 ± 21 in the E and G groups respectively. Uterine volume at 6 months reduced from 1018 ± 666mls to 622 ± 436 (p = 0.001) and from 1026 ± 756 to 908 ± 720 (p = 0.15) in the E and G groups respectively. There was a significant difference between groups for this parameter p = 0.01. All uterine arteries were patent at 24-h and 6 months. Complete (100%) fibroid infarction rates were 5(50%) and 2(20%) in the E and G groups respectively. None of the other outcome measures showed any between group differences. There were no re-interventions in either group. Conclusion The only significant between group differences was for a greater reduction in uterine volume at 6 months in the E group. A larger trial (estimate 172 subjects) is required to determine whether other apparent differences are clinically and statistically significant. Trial registration ISRCTN6734798

Intrinsic Hydrophobic Antibacterial Thin Film from Renewable Resources: Application in the Development of Anti-Biofilm Urinary Catheters

The use of renewable resources to develop functional materials is increasing in order to meet the sustainability challenges. In an era of inexorable evolution of antimicrobial resistance, there is a substantial increase in demand for the development of efficient antimicrobial thin film coating from renewable resources for public bacterial threats, food, biomedical, and industrial applications. In the present investigation, we have used cardanol, a phenolic compound having unsaturated hydrophobic tail isolated from cashew fruits, and linseed oil, a vegetable oil and an important biobased building block, which are cheap and easy to regenerate. This study reports the synthesis of cardanol based metal complexes having unsaturated hydrophobic unit and acrylated epoxidized linseed oil (AELO) prepared via epoxidation of double bonds followed by acrylation. The double bond present in the metal complexes and AELO is prone to form assembled thin film under atmospheric conditions, without the need of any initiators. Assembled thin film is one of the important aspects of nanotechnology holding a wide range of applications. ¹H NMR and FT-IR analysis revealed the existence of a strong interaction between ligand and metal, which paves a way to develop a nonleachable metal based thin film coating. The leaching behavior of thin film coating was investigated under various aggressive conditions with the aid of UV–vis spectroscopy. The mechanical properties of assembled thin film coating material composed of cardanol-based metal complex and AELO are described using oscillatory rheology. Morphological and SAXD analysis clearly revealed the formation of the assembled structure in thin films. Thermal response of these materials has been investigated using TGA and DSC measurements. Intrinsic hydrophobic character was identified by contact angle measurement. Antimicrobial and biofilm inhibitory behavior of synthesized compounds and thin films were investigated against various human pathogenic bacterial strains. The assembled thin film coated catheter tube completely inhibits the biofilm formation of uropathogenic Escherichia coli (UPEC). Thus, the developed thin film coating material holds promise to be used as metal enabled, nonleachable coating materials for public bacterial threats, and food and biomedical applications. In particular, this material can be potentially used for developing urinary catheter tubes with antibacterial properties

Disassembly of Bacterial Biofilms by the Self-Assembled Glycolipids Derived from Renewable Resources

More than 80% of chronic infections of bacteria are caused by biofilms. It is also a long-term survival strategy of the pathogens in a nonhost environment. Several amphiphilic molecules have been used in the past to potentially disrupt biofilms; however, the involvement of multistep synthesis, complicated purification and poor yield still remains a major problem. Herein, we report a facile synthesis of glycolipid based surfactant from renewable feedstocks in good yield. The nature of carbohydrate unit present in glycolipid influence the ring chain tautomerism, which resulted in the existence of either cyclic structure or both cyclic and acyclic structures. Interestingly, these glycolipids self-assemble into gel in highly hydrophobic solvents and vegetable oils, and displayed foam formation in water. The potential application of these self-assembled glycolipids to disrupt preformed biofilm was examined against various pathogens. It was observed that glycolipid <b>6a</b> disrupts <i>Staphylococcus aureus</i> and <i>Listeria monocytogenes</i> biofilm, while the compound <b>6c</b> was effective in disassembling uropathogenic <i>E. coli</i> and <i>Salmonella enterica</i> Typhimurium biofilms. Altogether, the supramolecular self-assembled materials, either as gel or as surfactant solution could be potentially used for surface cleansing in hospital environments or the food processing industries to effectively reduce pathogenic biofilms