Reactive inkjet printing and functional inks : a versatile route to new programmed materials

Starting as an ink dispensing tool for documents and images, inkjet printing has emerged as an important instrument for delivering reactive fluids, into a means for creating new, programmed materials. Inkjet is a processing technology with some very unique capabilities, which allows the handling of materials in the picoliter range, and the creation of functionality in new, previously unexplored ways. In particular, drop-on-demand technology provides the chance to dispense liquids in picoliter/nanoliter quantities to very specific locations, with minimal material loss, and in a contact-free manner. This dramatic scale-down of production, not just miniaturization but "nanonization", affords materials that would be either too costly or otherwise inaccessible by other manners. As this is still an emerging technology, there remain a lot of opportunities to pioneer new applications. The underlying, unifying concept behind the chapters of this thesis has been an interest in investigating how inkjet printing, combined with reactive inks, can lead to new applications, new devices, and new materials, wherein unique functionality is imparted as a direct result of the confluence between microfluidic processing, chemistry, and life science. The ability to deliver uniform, sub-nanoliter droplets to specific locations opens up new possibilities that did not exist before. Inherent in the geometry of such droplets, the volume of liquid dispensed also offers some special utility. Based on the aforementioned diameters, drop-on-demand inkjet printing can deliver volumes in the range of approximately 0.5 to 1,000 pL; the direct writing attributes of inkjet ensure that these droplets are not only precise, but can be delivered to a specific location, giving them a "home address". This combination of precise, reproducible, small aliquots and precision deposition is especially important for preparing high-density analytical arrays, as discussed in Chapter 1 on inkjet printing of proteins. In the case of highly specialized proteins such as reactive enzymes or antibodies, where available materials are often limited, the ability to dispense precise quantities in a reproducible fashion means that small amounts of precious material can be used parsimoniously to perform thousands of experiments without compromising the quality of the data. For drop-on-demand printing, droplets normally produced by inkjet printing are commonly in the range of 10 to 125 µm in diameter, depending on the physical characteristics of the fluid, the nozzle used, and the printing conditions; taking advantage of the this aliquot size has some unique attributes that make dispensing highly suitable to materials science challenges that have gone unmet. In the second chapter of this thesis, this size domain is taken advantage of for use in tissue engineering, where it is used to create soft, cell-scale porogenic structures by the use of a reversible, rapid alginate gelation reaction to freeze droplet structures in place. By switching to a continuous inkjet device, larger volumes of beads in the size domain of 100 to 500 µm can be achieved, opening up prospects for pore sizes matching those needed for hosting capillaries. By incorporating reversible hydrogels as a motif in these applications, these controlled cell-scale dimensions can be retained during key processing steps, and then removed (or eroded) later after they have served their function. Extending the concept to the task of dispensing living cells, in Chapter 3, printed alginate structures are used for cell encapsulation. By adjusting the printing conditions to prevent jet break-up before alginate hardening, continuous, one-dimensional "living threads" can be created, which allow for cell cultures to be handled and woven into desired complex patterns. In addition to their role as basic building materials for tissue engineering scaffolds, the alginate threads provide a stable, bio-friendly environment for culturing different cell types, with cells exhibiting a high post-processing viability rate. In Chapter 4, the lower limits of single cell printing are explored, in the concept of "one cell-one well", where the attributes of inkjet printing are used to dispense individual cells. By careful selection of droplet size and accounting of cell concentrations, the statistical probability of single cell printing can be optimized, yielding spatially addressable arrays of isolated living cell cultures on a surface. Additional steps necessary to prevent cells from dehydration are also outlined, offering access to high density arrays of isolated living single cells on glass slides, where each individual droplet acts as independent nanoincubator, hosting intrinsically monoseptic cell cultures in parallel. In addition to describing the theoretical limits of single-pass cell printing experiment designs, an outline is given for experimental designs for tuning single particulate dispensing probability to any value desired between 0 and 1. The focus of Chapter 5 relates to reactive inkjet printing of ultrathin films on surfaces. For systems with moderately good surface wetting, such as polar solvents on glass or metal oxides, inkjet printed droplets result in features ranging approximately from 20 to 300 µm in diameter per droplet. By first printing a thiol-functionalized heterochelic linker and covalently bonding it to the print surface, the surface will accommodate subsequent thiol-ene click reactions only with original monolayer, and only where the first and second deposition features overlap. This combination of spatial selectivity as well as chemoselectivity allows for the preparation of a wide range of monolayers on a printed surface, in a format well-suited to automated surface characterization techniques, as was illustrated using XPS. In Chapters 6, two different categories of irreversible polymerization reactions are described, where print features are reacted in a specific pattern that is process unique. Printable ionogels are developed, which impart conductivity to printed patterns, and consequently, functionality to only those locations where the material has been deposited. Also in Chapter 6, the first example of a moisture-sensitive reactive printing is outlined, where a diisocyanate is combined with different polyols within seconds to create highly crosslinked, ultra-stiff surfaces, which can be built up into three dimensions by successive layering. The topics outlined in this thesis are intended to illustrate the breadth of how inkjet technology can be utilized to support a diverse field of materials science applications — particularly when coupled with modular, off-the-shelf synthetic transformations. The incorporation of synthetic chemistry into inkjet extends the application of inkjet from dispensing static materials merely from a cartridge onto a target, into a dynamic tool for transforming these materials into something new. At the same time, inkjet printing and other allied microfluidics tools enable chemistry experiments (and by extension, life science experiments) on a scale that would otherwise be challenging to realize by other means. The two driving forces of high-throughput experiment design, miniaturization and automation, are both embodied in this dispensing technique, and consequently inkjet printing is a rapidly evolving discipline; it is the intent of this work and the examples given to underscore the diversity offered by this technology

Human Resource Flexibility as a Mediating Variable Between High Performance Work Systems and Performance

Much of the human resource management literature has demonstrated the impact of high performance work systems (HPWS) on organizational performance. A new generation of studies is emerging in this literature that recommends the inclusion of mediating variables between HPWS and organizational performance. The increasing rate of dynamism in competitive environments suggests that measures of employee adaptability should be included as a mechanism that may explain the relevance of HPWS to firm competitiveness. On a sample of 226 Spanish firms, the study’s results confirm that HPWS influences performance through its impact on the firm’s human resource (HR) flexibility

Gendering the careers of young professionals: some early findings from a longitudinal study. in Organizing/theorizing: developments in organization theory and practice

Wonders whether companies actually have employees best interests at heart across physical, mental and spiritual spheres. Posits that most organizations ignore their workforce – not even, in many cases, describing workers as assets! Describes many studies to back up this claim in theis work based on the 2002 Employment Research Unit Annual Conference, in Cardiff, Wales

Study of the lineshape of the chi(c1) (3872) state

A study of the lineshape of the chi(c1) (3872) state is made using a data sample corresponding to an integrated luminosity of 3 fb(-1) collected in pp collisions at center-of-mass energies of 7 and 8 TeV with the LHCb detector. Candidate chi(c1)(3872) and psi(2S) mesons from b-hadron decays are selected in the J/psi pi(+)pi(-) decay mode. Describing the lineshape with a Breit-Wigner function, the mass splitting between the chi(c1 )(3872) and psi(2S) states, Delta m, and the width of the chi(c1 )(3872) state, Gamma(Bw), are determined to be (Delta m=185.598 +/- 0.067 +/- 0.068 Mev,)(Gamma BW=1.39 +/- 0.24 +/- 0.10 Mev,) where the first uncertainty is statistical and the second systematic. Using a Flatte-inspired model, the mode and full width at half maximum of the lineshape are determined to be (mode=3871.69+0.00+0.05 MeV.)(FWHM=0.22-0.04+0.13+0.07+0.11-0.06-0.13 MeV, ) An investigation of the analytic structure of the Flatte amplitude reveals a pole structure, which is compatible with a quasibound D-0(D) over bar*(0) state but a quasivirtual state is still allowed at the level of 2 standard deviations

Measurement of the CKM angle γγ in B±→DK±B^\pm\to D K^\pm and B±→Dπ±B^\pm \to D π^\pm decays with D→KS0h+h−D \to K_\mathrm S^0 h^+ h^-

A measurement of $CP$-violating observables is performed using the decays $B^\pm\to D K^\pm$ and $B^\pm\to D \pi^\pm$, where the $D$ meson is reconstructed in one of the self-conjugate three-body final states $K_{\mathrm S}\pi^+\pi^-$ and $K_{\mathrm S}K^+K^-$ (commonly denoted $K_{\mathrm S} h^+h^-$). The decays are analysed in bins of the $D$-decay phase space, leading to a measurement that is independent of the modelling of the $D$-decay amplitude. The observables are interpreted in terms of the CKM angle $\gamma$. Using a data sample corresponding to an integrated luminosity of $9\,\text{fb}^{-1}$ collected in proton-proton collisions at centre-of-mass energies of $7$, $8$, and $13\,\text{TeV}$ with the LHCb experiment, $\gamma$ is measured to be $\left(68.7^{+5.2}_{-5.1}\right)^\circ$. The hadronic parameters $r_B^{DK}$, $r_B^{D\pi}$, $\delta_B^{DK}$, and $\delta_B^{D\pi}$, which are the ratios and strong-phase differences of the suppressed and favoured $B^\pm$ decays, are also reported

Measurement of forward charged hadron flow harmonics in peripheral PbPb collisions at √sNN = 5.02 TeV with the LHCb detector

Flow harmonic coefficients, v n , which are the key to studying the hydrodynamics of the quark-gluon plasma (QGP) created in heavy-ion collisions, have been measured in various collision systems and kinematic regions and using various particle species. The study of flow harmonics in a wide pseudorapidity range is particularly valuable to understand the temperature dependence of the shear viscosity to entropy density ratio of the QGP. This paper presents the first LHCb results of the second- and the third-order flow harmonic coefficients of charged hadrons as a function of transverse momentum in the forward region, corresponding to pseudorapidities between 2.0 and 4.9, using the data collected from PbPb collisions in 2018 at a center-of-mass energy of 5.02 TeV . The coefficients measured using the two-particle angular correlation analysis method are smaller than the central-pseudorapidity measurements at ALICE and ATLAS from the same collision system but share similar features

Helium identification with LHCb

The identification of helium nuclei at LHCb is achieved using a method based on measurements of ionisation losses in the silicon sensors and timing measurements in the Outer Tracker drift tubes. The background from photon conversions is reduced using the RICH detectors and an isolation requirement. The method is developed using pp collision data at √(s) = 13 TeV recorded by the LHCb experiment in the years 2016 to 2018, corresponding to an integrated luminosity of 5.5 fb-1. A total of around 105 helium and antihelium candidates are identified with negligible background contamination. The helium identification efficiency is estimated to be approximately 50% with a corresponding background rejection rate of up to O(10^12). These results demonstrate the feasibility of a rich programme of measurements of QCD and astrophysics interest involving light nuclei

Curvature-bias corrections using a pseudomass method

Momentum measurements for very high momentum charged particles, such as muons from electroweak vector boson decays, are particularly susceptible to charge-dependent curvature biases that arise from misalignments of tracking detectors. Low momentum charged particles used in alignment procedures have limited sensitivity to coherent displacements of such detectors, and therefore are unable to fully constrain these misalignments to the precision necessary for studies of electroweak physics. Additional approaches are therefore required to understand and correct for these effects. In this paper the curvature biases present at the LHCb detector are studied using the pseudomass method in proton-proton collision data recorded at centre of mass energy √(s)=13 TeV during 2016, 2017 and 2018. The biases are determined using Z→μ + μ - decays in intervals defined by the data-taking period, magnet polarity and muon direction. Correcting for these biases, which are typically at the 10-4 GeV-1 level, improves the Z→μ + μ - mass resolution by roughly 18% and eliminates several pathological trends in the kinematic-dependence of the mean dimuon invariant mass

Study of CP violation in B0 → DK⋆(892)0 decays with D → Kπ(ππ), ππ(ππ), and KK final states

A measurement of CP-violating observables associated with the interference of B0 → D0K⋆ (892)0 and B0 → D¯ 0K⋆ (892)0 decay amplitudes is performed in the D0 → K∓π ±(π +π −), D0 → π +π −(π +π −), and D0 → K+K− fnal states using data collected by the LHCb experiment corresponding to an integrated luminosity of 9 fb−1 . CP-violating observables related to the interference of B0 s → D0K¯ ⋆ (892)0 and B0 s → D¯ 0K¯ ⋆ (892)0 are also measured, but no evidence for interference is found. The B0 observables are used to constrain the parameter space of the CKM angle γ and the hadronic parameters r DK⋆ B0 and δ DK⋆ B0 with inputs from other measurements. In a combined analysis, these measurements allow for four solutions in the parameter space, only one of which is consistent with the world average