Functional Emulsions via Thiol-Ene Chemistry

Polymer particles (micro to nano) with tunable functionality have emerged as a promising and viable technology platform for applications including coatings, cosmetics, nanomedicine, and imaging. Unfortunately, the lengthy polymerization time and lack of intrinsic functionality in the monomers used to fabricate particles is an industrial challenge. Thiol-ene chemistry cirmcumvents these limitations with very rapid polymerization kinetics, high reaction yields, with supressed side reactions and inherent functionality. This dissertation demonstrates the utility of thiol-ene/yne polymerization in miniemulsion and microfluidics to generate functional materials in a one-pot-method. The functionality is typically generated via off-stoichiometry thiol-ene (OSTE) resins which allow for either excess SH or alkene/yne functionality to be present throughout the material. The accessability of these functional groups are proven via infrared spectroscopy, confocal and optical microscopy. The first chapter focuses on the burgeoning field of thiol-ene/yne chemistry within multiphase emulsions and introduces innovative methods to generate functional particles/materials. Chapter II describes the first thiol-ene miniemulsion process where surfactant concentration, ultrasonication time/amplitude, and OSTE resins are explored. Chapter III expands the miniemulsion process to include thiol-yne resins in addition to the ability to encapsulate hydrophobic materials such as modified silver nanoparticles. Chapter IV highlights the utility of thiol-ene resins within microfluidics to generate unique multiphase particles that can outperform traditional acrylate-based resins. The application of thiol-ene chemistry in emulsions introduces a new class of functional materials which can be easily translated into exicisting technologies

Functional, Sub-100 nm Polymer Nanoparticles \u3ci\u3evia\u3c/i\u3e Thiol-ene Miniemulsion Photopolymerization

In this work, sub-100 nm crosslinked polythioether nanoparticles were synthesized via thiol–ene photopolymerization in miniemulsion using high-energy homogenization. The effects of the miniemulsion formulation and homogenization parameters – including inhibitor concentration, surfactant concentration, organic weight fraction, ultrasonication time and amplitude – on nanoparticle size and size distribution were investigated. Thiol–ene nanoparticles with a mean particle diameter of 46 nm were obtained under optimized conditions for the current system at 2.5 wt% organic fraction and 20 mM surfactant concentration. In an effort to demonstrate potential utility of thiol–ene nanoparticles, we exploit the step-growth radical mechanism of thiol–ene photopolymerization under non-stoichiometric conditions to fabricate functional nanoparticles that express excess thiol or alkene at the particle surface. We show that these excess functional groups can be utilized as reactive handles in thiol-Michael and radical-mediated thiol–ene reactions for immobilization of fluorescent moieties via postpolymerization modification

Destruction of Opportunistic Pathogens Via Polymer Nanoparticle-Mediated Release of Plant-Based Antimicrobial Payloads

The synthesis of antimicrobial thymol/carvacrol‐loaded polythioether nanoparticles (NPs) via a one‐pot, solvent‐free miniemulsion thiol‐ene photopolymerization process is reported. The active antimicrobial agents, thymol and carvacrol, are employed as “solvents” for the thiol‐ene monomer phase in the miniemulsion to enable facile high capacity loading (≈50% w/w), excellent encapsulation efficiencies (\u3e95%), and elimination of all postpolymerization purification processes. The NPs serve as high capacity reservoirs for slow‐release and delivery of thymol/carvacrol‐combination payloads that exhibit inhibitory and bactericidal activity (\u3e99.9% kill efficiency at 24 h) against gram‐positive and gram‐negative bacteria, including both saprophytic (Bacillus subtilis ATCC 6633 and Escherichia coli ATCC 25922) and pathogenic species (E. coli ATCC 43895, Staphylococcus aureus RN6390, and Burkholderia cenocepacia K56‐2). This report is among the first to demonstrate antimicrobial efficacy of essential oil‐loaded nanoparticles against B. cenocepacia – an innately resistant opportunistic pathogen commonly associated with debilitating respiratory infections in cystic fibrosis. Although a model platform, these results point to promising pathways to particle‐based delivery of plant‐derived extracts for a range of antimicrobial applications, including active packaging materials, topical antiseptics, and innovative therapeutics

Synthesis and evaluation of thermally-responsive coatings based upon Diels–Alder chemistry and renewable materials

A soybean based coating with thermally responsive Diels–Alder linkages has been prepared following an automotive 2-component formulation. The resulting coatings displayed the capability to be healed following physical deformation by a thermal stimulus, and such a material has significant potential for end users. Various curing agents were employed, and resulted in variation of scratch resistance and re-healablity. Different thermally responsive soybean resins were synthesized to have varying amounts reversible and nonreversible linkages when incorporated into the coating. Additionally, different isocyanates were added at differing ratios of NCO:OH in search of the optimum coating. It was found through the analysis of rehealability, hardness, gloss, and adhesion that the optimal combination was an acetylated resin (no irreversible crosslinks) with 54% reversible Diels–Alder linkages at an NCO:OH ratio of 5:1 using isophorone diiscocyanate. Materials were evaluated via differential scanning calorimetry (DSC), scratch resistance, Koenig hardness, gloss measurements, and topographical analysis

A Bio-Based Pro-Antimicrobial Polymer Network Via Degradable Acetal Linkages

The synthesis of a fully degradable, bio-based, sustained release, pro-antimicrobial polymer network comprised of degradable acetals (PANDA) is reported. The active antimicrobial agent – p-anisaldehyde (pA) (an extract from star anise) – was converted into a UV curable acetal containing pro-antimicrobial monomer and subsequently photopolymerized into a homogenous thiol-ene network. Under neutral to acidic conditions (pH \u3c 8), the PANDAs undergo surface erosion and exhibit sustained release of pA over 38 days. The release of pA from PANDAs was shown to be effective against both bacterial and fungal pathogens. From a combination of confocal microscopy and transmission electron microscopy, we observed that the released pA disrupts the cell membrane. Additionally, we demonstrated that PANDAs have minimal cytotoxicity towards both epithelial cells and macrophages. Although a model platform, these results point to promising pathways for the design of fully degradable sustained-release antimicrobial systems with potential applications in agriculture, pharmaceuticals, cosmetics, household/personal care, and food industries

Endotracheal tube cuff pressure assessment maneuver induces drop of expired tidal volume in the postoperative of coronary artery bypass grafting

Background: Previous investigations reported that the cuff pressure (CP) can decrease secondary to the CP evaluation itself. However is not established in literature if this loss of CP is able to generate alterations on expired tidal volume (ETV). Therefore, the aim of this study was to evaluate the potential consequences of the endotracheal CP assessment maneuver on CP levels and ETV in the early postoperative of coronary artery bypass grafting (CABG).Methods: A total of 488 patients were analyzed. After the operation, the lungs were ventilated in pressure-assist control mode and the same ventilatory settings were adjusted for all patients. After intensive care unit arrival, the cuff was fully deflated and then progressively inflated by air injection, to promote a minimal volume to occlude the trachea. To assist the cuff inflation and the air leakage identification, the graphical monitoring of the volume-time curve was adopted. After 20 minutes a first cuff pressure evaluation was performed (P1) and a second measurement (P2) was taken after 20 minutes with an analog manometer. ETV was obtained always pre and post P1 measurement.Results: the CP assessment maneuver promoted a significant drop of P2 in relation to P1 when the manometer was attached to the pilot balloon (p < 0.0001). When compared the moments, pre-P1 versus post-P1, a significant drop of the ETV was also observed (p < 0.0001).Conclusion: the CP assessment maneuver promoted a significant decrease in CP values and occurrence of air leakage with reduction of ETV in the early postoperative of CABG.Universidade Federal de São Paulo, Dept Med, Cardiol Discipline, Pirajussara Hosp,Escola Paulista Med, BR-04024002 São Paulo, BrazilUniversidade Federal de São Paulo, Dept Med, Cardiol Discipline, São Paulo Hosp,Escola Paulista Med, BR-04024002 São Paulo, BrazilUniversidade Federal de São Paulo, Physiotherapy Sch, Dept Human Movement Sci, BR-11060001 Santos, BrazilUniversidade Federal de São Paulo, Dept Med, Pneumol Discipline, São Paulo Hosp,Escola Paulista Med, BR-04039002 São Paulo, BrazilUniversidade Federal de São Paulo, Dept Med, Cardiovasc Surg Discipline, Pirajussara Hosp,Escola Paulista Med, BR-04024002 São Paulo, BrazilUniversidade Federal de São Paulo, Dept Med, Cardiovasc Surg Discipline, São Paulo Hosp,Escola Paulista Med, BR-04024002 São Paulo, BrazilUniversidade Federal de São Paulo, Escola Paulista Med, Cardiol Discipline, BR-04024002 São Paulo, BrazilUniversidade Federal de São Paulo, Dept Med, Cardiol Discipline, Pirajussara Hosp,Escola Paulista Med, BR-04024002 São Paulo, BrazilUniversidade Federal de São Paulo, Dept Med, Cardiol Discipline, São Paulo Hosp,Escola Paulista Med, BR-04024002 São Paulo, BrazilUniversidade Federal de São Paulo, Physiotherapy Sch, Dept Human Movement Sci, BR-11060001 Santos, BrazilUniversidade Federal de São Paulo, Dept Med, Pneumol Discipline, São Paulo Hosp,Escola Paulista Med, BR-04039002 São Paulo, BrazilUniversidade Federal de São Paulo, Dept Med, Cardiovasc Surg Discipline, Pirajussara Hosp,Escola Paulista Med, BR-04024002 São Paulo, BrazilUniversidade Federal de São Paulo, Dept Med, Cardiovasc Surg Discipline, São Paulo Hosp,Escola Paulista Med, BR-04024002 São Paulo, BrazilUniversidade Federal de São Paulo, Escola Paulista Med, Cardiol Discipline, BR-04024002 São Paulo, BrazilWeb of Scienc

Unified force law for granular impact cratering

Experiments on the low-speed impact of solid objects into granular media have been used both to mimic geophysical events and to probe the unusual nature of the granular state of matter. Observations have been interpreted in terms of conflicting stopping forces: product of powers of projectile depth and speed; linear in speed; constant, proportional to the initial impact speed; and proportional to depth. This is reminiscent of high-speed ballistics impact in the 19th and 20th centuries, when a plethora of empirical rules were proposed. To make progress, we developed a means to measure projectile dynamics with 100 nm and 20 us precision. For a 1-inch diameter steel sphere dropped from a wide range of heights into non-cohesive glass beads, we reproduce prior observations either as reasonable approximations or as limiting behaviours. Furthermore, we demonstrate that the interaction between projectile and medium can be decomposed into the sum of velocity-dependent inertial drag plus depth-dependent friction. Thus we achieve a unified description of low-speed impact phenomena and show that the complex response of granular materials to impact, while fundamentally different from that of liquids and solids, can be simply understood

The Role of the Lactate Dehydrogenase and the Effect of Prone Position during Ventilator-induced Lung Injury

To examine the impact of lactate dehydrogenase (LDH) as an early marker of ventilator-induced lung injury (VILI) and the effect of prone position during the VILI, we ventilated 28 normal white rabbits (10 supine, 10 prone, 8 controls) for 6 hr or until PaO2/FIO2 ratio was <200 mmHg. We applied an identical injurious ventilatory pattern (peak inspiratory pressure of 35 cmH2O with a PEEP of 3 cmH2O, I:E ratio of 1:2, and FIO2 of 0.40) in the supine and prone group. VILI was assessed by oxygenation, gravimetric analysis and histologic grading. Serum levels of LDH progressively increased significantly during the VILI (supine and prone groups) as compared with controls. There was a significant negative correlation between oxygenation and LDH levels (r=-0.619, p<0.001). Wet weight/dry weight ratios (WW/DW) and histologic scores for dependent regions were significantly higher in the supine than the prone group. There were no differences in WW/DW and histologic scores for nondependent regions between the supine and prone group. These findings suggest that serum LDH levels might be an early marker of severity of lung injury. The prone position resulted in a less severe and more homogenous distribution of VILI

The influence of diet and environment on the gut microbial community of field crickets

The extent to which diet and environment influence gut community membership (presence or absence of taxa) and structure (individual taxon abundance) is the subject of growing interest in microbiome research. Here, we examined the gut bacterial communities of three cricket groups: (1) wild caught field crickets, (2) laboratory-reared crickets fed cat chow, and (3) laboratory-reared crickets fed chemically defined diets. We found that both environment and diet greatly altered the structure of the gut bacterial community. Wild crickets had greater gut microbial diversity and higher Firmicutes to Bacteroidetes ratios, in contrast to laboratory-reared crickets. Predictive metagenomes revealed that laboratory-reared crickets were significantly enriched in amino acid degradation pathways, while wild crickets had a higher relative abundance of peptidases that would aid in amino acid release. Although wild and laboratory animals differ greatly in their bacterial communities, we show that the community proportional membership remains stable from Phylum to Family taxonomic levels regardless of differences in environment and diet, suggesting that endogenous factors, such as host genetics, have greater control in shaping gut community membership

A comparative analysis of Patient-Reported Expanded Disability Status Scale tools.

BACKGROUND: Patient-Reported Expanded Disability Status Scale (PREDSS) tools are an attractive alternative to the Expanded Disability Status Scale (EDSS) during long term or geographically challenging studies, or in pressured clinical service environments. OBJECTIVES: Because the studies reporting these tools have used different metrics to compare the PREDSS and EDSS, we undertook an individual patient data level analysis of all available tools. METHODS: Spearman's rho and the Bland-Altman method were used to assess correlation and agreement respectively. RESULTS: A systematic search for validated PREDSS tools covering the full EDSS range identified eight such tools. Individual patient data were available for five PREDSS tools. Excellent correlation was observed between EDSS and PREDSS with all tools. A higher level of agreement was observed with increasing levels of disability. In all tools, the 95% limits of agreement were greater than the minimum EDSS difference considered to be clinically significant. However, the intra-class coefficient was greater than that reported for EDSS raters of mixed seniority. The visual functional system was identified as the most significant predictor of the PREDSS-EDSS difference. CONCLUSION: This analysis will (1) enable researchers and service providers to make an informed choice of PREDSS tool, depending on their individual requirements, and (2) facilitate improvement of current PREDSS tools.University of Southampton and National Institute of Health Research (NIHR)