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"Irvine, Derek"
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The power of thanks : how social recognition empowers employees and creates a best place to work
\"The most powerful word in your leadership vocabulary is. THANKS!..Building a fully engaged, energized workforce is the key to business success. The Power of Thanks reveals how leading companies like Intuit, JetBlue Airways, IHG, Symantec, ConAgra Foods, and The Hershey Company empower employees through social recognition, in which the practice of mutual appreciation and trust directs and rewards higher performance...Eric Mosley and Derek Irvine, executives at the world-renowned employee recognition firm Globoforce, explain why social recognition is so powerful and how you can apply it in your company. Case by case, they show how a carefully.planned and consistently executed Culture of Recognition business strategy inspires:. Greater employee engagement and loyalty. Stronger, more unified teams and departments. A creative, innovative company culture. Improved customer satisfaction. Increased profitability and organizational health..Mosley and Irvine provide practical advice and proven examples for devising a powerful, growth-generating strategy that modernizes employee recognition for today's social, global, multi-generational and 24x7 wired workforce...When employees participate in a culture that makes everyone a stakeholder in the organization's success, positive energy spreads like wildfire, and business results follow. Something so simple and powerful might work like magic, but it's really just common sense. It's smart management. It's long-term thinking...It's The Power of Thanks.\"-- Provided by publisher.
Book
Combinatorial discovery of polymers resistant to bacterial attachment
Bacterial attachment and biofilm formation are problematic for medical devices. Hook
et al
. present a high-throughput method to find materials that resist bacterial attachment and colonization.
Bacterial attachment and subsequent biofilm formation pose key challenges to the optimal performance of medical devices. In this study, we determined the attachment of selected bacterial species to hundreds of polymeric materials in a high-throughput microarray format. Using this method, we identified a group of structurally related materials comprising ester and cyclic hydrocarbon moieties that substantially reduced the attachment of pathogenic bacteria (
Pseudomonas aeruginosa, Staphylococcus aureus
and
Escherichia coli
). Coating silicone with these 'hit' materials achieved up to a 30-fold (96.7%) reduction in the surface area covered by bacteria compared with a commercial silver hydrogel coating
in vitro
, and the same material coatings were effective at reducing bacterial attachment
in vivo
in a mouse implant infection model. These polymers represent a class of materials that reduce the attachment of bacteria that could not have been predicted to have this property from the current understanding of bacteria-surface interactions.
Journal Article
Terpene‐Maleate Based Resins for Stereolithography: Advancing Sustainable 3D Printing
Additive Manufacturing (AM), particularly stereolithography (SLA), offers great flexibility for producing complex structures. However, the limited availability of photocurable and sustainable resins remains a major challenge. Therefore, the development of ‘greener’ alternatives is imperative to establish a sustainable cycle within the AM industry. To address this, we developed a novel terpene‐based monomer, monoperillyl maleate (PeryMal), which is both degradable and cross‐linkable, offering a greener alternative to traditional petroleum‐based acrylic resins. The synthesis was carried out using the bio‐derived solvent 2‐methyltetrahydrofuran (2‐MeTHF) to further enhance sustainability. PeryMal was blended with the water‐soluble monomer ACMO at various ratios and successfully 3D printed. The ACMO‐blend 60, with the highest PeryMal content, showed excellent printability, a glass transition temperature (Tg) of 25°C–30°C, and thermal stability up to 400°C. It also demonstrated full degradation in alkaline conditions (pH 9) within 24 h and partial degradation at pH 2 over 28 days. To further improve sustainability, PeryMal was also blended with bio‐based isobornyl methacrylate (iBoMA). The resulting iBoMA‐blend 60 also printed well (PS 5) and exhibited a higher Tg of 65°C–90°C. These results highlight the potential of PeryMal‐based systems for creating sustainable, functional materials for SLA printing. This study presents the design and synthesis of a novel, degradable terpene‐based crosslinker, monoperillyl maleate (PeryMal), using the bio‐derived solvent 2‐MeTHF to reduce acrylic resin use in SLA printing. Its printability and degradability were demonstrated through formulations with two commercial monomers, offering a more sustainable approach to photopolymer development for additive manufacturing.
Journal Article
Ring opening polymerisation of ɛ-caprolactone with novel microwave magnetic heating and cyto-compatible catalyst
We report on the ring-opening polymerization of ɛ-caprolactone incorporated with a magnetic susceptible catalyst, FeCl 3 , via the use of microwave magnetic heating (HH) which primarily heats the bulk with a magnetic field (H-field) from an electromagnetic field (EMF). Such a process was compared to more commonly used heating methods, such as conventional heating (CH), i.e., oil bath, and microwave electric heating (EH), which is also referred to as microwave heating that primarily heats the bulk with an electric field (E-field). We identified that the catalyst is susceptible to both the E-field and H-field heating, and promoted the heating of the bulk. Which, we noticed such promotion was a lot more significant in the HH heating experiment. Further investigating the impact of such observed effects in the ROP of ɛ-caprolactone, we found that the HH experiments showed a more significant improvement in both the product Mwt and yield as the input power increased. However, when the catalyst concentration was reduced from 400:1 to 1600:1 (Monomer:Catalyst molar ratio), the observed differentiation in the Mwt and yield between the EH and the HH heating methods diminished, which we hypothesized to be due to the limited species available that were susceptible to microwave magnetic heating. But comparable product results between the HH and EH heating methods suggest that the HH heating method along with a magnetic susceptible catalyst could be an alternative solution to overcome the penetration depth problem associated with the EH heating methods. The cytotoxicity of the produced polymer was investigated to identify its potential application as biomaterials.
Journal Article
Droplet Microfluidic Optimisation Using Micropipette Characterisation of Bio-Instructive Polymeric Surfactants
Droplet microfluidics can produce highly tailored microparticles whilst retaining monodispersity. However, these systems often require lengthy optimisation, commonly based on a trial-and-error approach, particularly when using bio-instructive, polymeric surfactants. Here, micropipette manipulation methods were used to optimise the concentration of bespoke polymeric surfactants to produce biodegradable (poly(d,l-lactic acid) (PDLLA)) microparticles with unique, bio-instructive surface chemistries. The effect of these three-dimensional surfactants on the interfacial tension of the system was analysed. It was determined that to provide adequate stabilisation, a low level (0.1% (w/v)) of poly(vinyl acetate-co-alcohol) (PVA) was required. Optimisation of the PVA concentration was informed by micropipette manipulation. As a result, successful, monodisperse particles were produced that maintained the desired bio-instructive surface chemistry.
Journal Article
Additive manufacture of complex 3D Au-containing nanocomposites by simultaneous two-photon polymerisation and photoreduction
The fabrication of complex three-dimensional gold-containing nanocomposite structures by simultaneous two-photon polymerisation and photoreduction is demonstrated. Increased salt delivers reduced feature sizes down to line widths as small as 78 nm, a level of structural intricacy that represents a significant advance in fabrication complexity. The development of a general methodology to efficiently mix pentaerythritol triacrylate (PETA) with gold chloride hydrate (HAuCl
4
∙3H
2
O) is reported, where the gold salt concentration is adjustable on demand from zero to 20 wt%. For the first-time 7-Diethylamino-3-thenoylcoumarin (DETC) is used as the photoinitiator. Only 0.5 wt% of DETC was required to promote both polymerisation and photoreduction of up to 20 wt% of gold salt. This efficiency is the highest reported for Au-containing composite fabrication by two-photon lithography. Transmission Electron Microscopy (TEM) analysis confirmed the presence of small metallic nanoparticles (5.4 ± 1.4 nm for long axis / 3.7 ± 0.9 nm for short axis) embedded within the polymer matrix, whilst X-ray Photoelectron Spectroscopy (XPS) confirmed that they exist in the zero valent oxidation state. UV-vis spectroscopy defined that they exhibit the property of localised surface plasmon resonance (LSPR). The capability demonstrated in this study opens up new avenues for a range of applications, including plasmonics, metamaterials, flexible electronics and biosensors.
Journal Article
Facile Synthesis of Functionalised Hyperbranched Polymers for Application as Novel, Low Viscosity Lubricant Formulation Components
A novel, previously unreported, method for synthesising hyperbranched (HB) materials is detailed. Their use as additives to produce lubricant formulations that exhibit enhanced levels of wear protection and improved low-temperature oil viscosity and flow is also reported. The lubricant formulations containing HB additives were found to exhibit both significantly lower viscosities and improved in-use film-forming properties than the current industry standard formulations. To achieve this, alkyl methacrylate oligomers (predominantly dimers and trimers) were synthesised using catalytic chain transfer polymerisation. These were then used as functional chain transfer agents (CTA) to control the polymerisation of divinyl benzene (DVB) monomers to generate highly soluble, high polydispersity HB polymers. The level of dimer/trimer purification applied was varied to define its influence on both these HB resultant structures and the resultant HB additives’ performance as a lubricant additive. It was shown that, while the DVB acted as the backbone of the HB, the base oil solubility of the additive was imparted by the presence of the alkyl chains included in the structure via the use of the oligomeric CTAs.
Journal Article
Dielectrically Monitored Flow Synthesis of Functional Vaccine Adjuvant Mixtures via Microwave-Assisted Catalytic Chain Transfer Processing
A novel flow process to produce low-molecular-weight (Mwt) methacrylate oligomer mixtures that have potential as vaccine adjuvants and chain transfer agents (CTAs) is reported. The chemistry and process were designed to significantly reduce the number of stages required to manufacture methyl methacrylate oligomer-in-monomer mixtures with an oligomer Mwt range of dimers to pentamers and >50% conversion. Combining rapid in-flow, in situ catalytic chain transfer polymerization catalyst synthesis and volumetric microwave heating of the reaction medium resulted in catalyst flow synthesis being completed in <4 min, removing the need to pre-synthesize it. The steady-state operation was then successfully maintained with very low levels of external energy, as the process utilized the reaction exotherm. The microwave process outperformed a comparative conventionally heated system by delivering a 20% increase in process throughput with no change in final product quality or conversion. Additionally, combining flow and in situ catalyst processing enabled the use of a more oxidatively unstable catalyst. This allowed for in situ catalyst deactivation post-generation of the oligomers, such that residual catalyst did not need to be removed prior to preparing subsequent vaccine adjuvant or CTA screening formulations. Finally, dielectric property measurements were able to monitor the onset of reaction and steady-state operation.
Journal Article
Molecular Differentiated Initiator Reactivity in the Synthesis of Poly(caprolactone)-Based Hydrophobic Homopolymer and Amphiphilic Core Corona Star Polymers
Macromolecules that possess three-dimensional, branched molecular structures are of great interest because they exhibit significantly differentiated application performance compared to conventional linear (straight chain) polymers. This paper reports the synthesis of 3- and 4-arm star branched polymers via ring opening polymerisation (ROP) utilising multi-functional hydroxyl initiators and Sn(Oct)2 as precatalyst. The structures produced include mono-functional hydrophobic and multi-functional amphiphilic core corona stars. The characteristics of the synthetic process were shown to be principally dependent upon the physical/dielectric properties of the initiators used. ROP’s using initiators that were more available to become directly involved with the Sn(Oct)2 in the “in-situ” formation of the true catalytic species were observed to require shorter reaction times. Use of microwave heating (MWH) in homopolymer star synthesis reduced reaction times compared to conventional heating (CH) equivalents, this was attributed to an increased rate of “in-situ” catalyst formation. However, in amphiphilic core corona star formation, the MWH polymerisations exhibited slower propagation rates than CH equivalents. This was attributed to macro-structuring within the reaction medium, which reduced the potential for reaction. It was concluded that CH experiments were less affected by this macro-structuring because it was disrupted by the thermal currents/gradients caused by the conductive/convective heating mechanisms. These gradients are much reduced/absent with MWH because it selectively heats specific species simultaneously throughout the entire volume of the reaction medium. These partitioning problems were overcome by introducing additional quantities of the species that had been determined to selectively heat.
Journal Article
Exploiting Generative Design for 3D Printing of Bacterial Biofilm Resistant Composite Devices
As the understanding of disease grows, so does the opportunity for personalization of therapies targeted to the needs of the individual. To bring about a step change in the personalization of medical devices it is shown that multi‐material inkjet‐based 3D printing can meet this demand by combining functional materials, voxelated manufacturing, and algorithmic design. In this paper composite structures designed with both controlled deformation and reduced biofilm formation are manufactured using two formulations that are deposited selectively and separately. The bacterial biofilm coverage of the resulting composites is reduced by up to 75% compared to commonly used silicone rubbers, without the need for incorporating bioactives. Meanwhile, the composites can be tuned to meet user defined mechanical performance with ±10% deviation. Device manufacture is coupled to finite element modelling and a genetic algorithm that takes the user‐specified mechanical deformation and computes the distribution of materials needed to meet this under given load constraints through a generative design process. Manufactured products are assessed against the mechanical and bacterial cell‐instructive specifications and illustrate how multifunctional personalization can be achieved using generative design driven multi‐material inkjet based 3D printing. Multi‐material inkjet‐based 3D printing is used for the design and manufacture of personalized medical devices. A design optimization approach is used to specify the location of two different materials, each with a different moduli, but both with the ability to resist bacterial colonization (up to 75% better than medical silicones), such that they meet user‐defined, complex design constraints.
Journal Article