Submicron gas bubbles in water

Gas bubbles smaller than 1 micrometre in water, commonly referred to as nanobubbles, is a growing field of research and innovation. Applications range from medical imaging and drug delivery to mining industry and environmental remediation. Despite much activity, important questions remain – which are the mechanisms that allow small gas bubbles to be stable against dissolution and are stable nanobubbles really as common and easily generated as is often claimed?This work demonstrates that several common nanobubble generation methods can generate particle agglomerates or oil droplets which can be mistaken for bubbles, whereas stable nano- and microbubbles are less easy to generate than commonly believed. The results further suggest that stable bubbles are normally stable due to a shell of surface-active organic compounds, whereas other proposed stability mechanisms are less likely. An unexpected finding was that sorbitan surfactant stabilized air nanobubbles can form long-lived bubble agglomerates.Holographic Nanoparticle Tracking Analysis (H-NTA) is demonstrated as a powerful new method to detect and differentiate between bubbles and particles in the same dispersion. As H-NTA determines the refractive index of tracked objects, bubbles will differ very significantly from solid particles or oil droplets. The method also enables detection of different populations of particles, agglomerates and oil droplets in the same dispersion

The ‘Self-enterprising Care Taker’ on ‘Home Deployment’: Contesting Constructions of Femininity in Extended Military Family Deployment Support in Sweden

This study takes a critical feminist anti-militarist perspective on the function and purpose of the support that families of soldiers are provided by militaries during deployment. The context in focus is Swedish deployment support of extended families of soldiers, the material selected is from the website and the forum of the voluntary peer and mentor based support organization Invidzonen. Applying a Critical Discourse Analysis informed by feminist theory, the aim of the study was to identify how military power through deployment support attempts to naturalize and sustain hegemonic gender ideologies, roles and identities and unequal power relations between men and women. This study illustrates the changing and more subtle expression of military power in post-modern society and in Sweden. In social practices of deployment support, between women, the military discourse of ‘home deployment’ has been re-contextualized as valuable experience. The study argues that this has created a discourse of ‘self-enterprising home deployment’. It individualizes and conceals the political and militarized nature of women as a group preforming free or government subsidized care and emotional labour for the SAF. This discourse situates women in contradictory but subordinated positions, with expectations to simultaneously do care and emotional labour and focus on individual development. This normative but contesting notion of femininity within deployment support is termed as the ‘self-enterprising caretaker’

Construction Management and Design-Build/Fast Track Construction From the Perspective of a Generla Contractor

In the accompanying paper a method for blind (i.e., no calibration needed) estimation and compensation of the time errors in a time interleaved ADC system was presented. In this paper we evaluate this method. The Cramer-Rao bound is calculated, both for additive noise and random clock jitter. Monte-Carlo simulations have also been done to compare to the CRB. Finally, the estimation method is validated on measurements from areal time interleaved ADC system with 16 ADCs

Differentiating bulk nanobubbles from nanodroplets and nanoparticles

History has shown that it is not as easy as one might think to differentiate between bulk nanobubbles and nanodroplets or nanoparticles. It is generally easy to detect colloids (i.e. something that looks different, e.g. scatters light differently than its surrounding solvent), but less easy to determine the nature of these colloids. This has led to misinterpretations in the literature, where nanodroplets or nanoparticles have mistakenly been assumed to be nanobubbles. In this paper, we review a multitude of experimental methods and approaches to prove the existence of bulk nanobubbles. We conclude that combinations of optical detection with physical perturbations such as pressure or ultrasound, or phase-sensitive holographic methods are the most promising and convenient approaches

Nanobubbles in water - how to identify them and why they are stable

Gas bubbles smaller than 1 micrometer in water, commonly referred to as nanobubbles, is a growing field of research and innovation. Applications range from medical imaging and drug delivery to mining industry and environmental remediation. There are many possibilities but important questions remain – how is it possible for small gas bubbles to be stable against dissolution and how can they be detected and differentiated from solid particles and oil droplets ?In this work we demonstrate that several common nanobubble generation methods can generate contamination particles which can be mistaken for bubbles and that with sufficient cleanliness, neither particles, droplets or bubbles are generated. Theories on nanobubble stability that does not include impurities can thus be dismissed. (Paper 1). Lipid stabilization and the dynamic equilibrium model based on hydrophobic dirt particles appear to be the only valid models for nanobubble stability at present.We furthermore demonstrate Holographic Nanoparticle Tracking Analysis (H-NTA) as a powerful new method to detect and differentiate between nanobubbles and nanoparticles in the same solution (Paper 2). As H-NTA determines the refractive index of tracked objects, bubbles will differ very significantly from solid particles or oil droplets. The refractive index of a bubble also indicates the amount of adsorbed material as well as possible clustering of multiple bubbles. The method also powerfully enables detection of different particle populationsclose in size and refractive index in a dispersion. The size range is 0.3-0.4 mm to 1.5 mm

Resource constraints in health care - case studies on technical, allocative and economic efficiency

The scarcity of resources and the need to produce more with less is an ever-present reality for managers of health care organisations. Trends in healthcare costs are a widely acknowledged concern among policy-makers worldwide. Many factors will contribute to the evolution of future health care systems. They include changing demand and demand patterns, developments of medical technology, citizens' expectations of readily available high-quality services, the availability and capacity of health care resources, the purchasing power of citizens, and financing mechanisms. In the study, six cases – representing the operative and conservatory area of special care, an open care system, a major regional diagnostic support function, elderly care systems and a regional health care system – are analyzed. The main contributions of operations management to resource constraint problem are related to, but not limited to, how capacity of resources can be measured and managed. This study provides insight and a model for how resource constraints can be identified in all health care service production processes as well as in patient episodes. Applying technical, allocative and economic efficiency analysis provides tools for identifying and reducing the impact of resource constraints. Reducing the impact or eliminating bottlenecks increases the total capacity of a process or system with interdependent resources. The benefits of the analysis increase as its scope analysis is extended to include the regional service network. Efficiency improvement efforts should focus on constrained resources, as a system's capacity can only be increased by increasing the capacity of these resources. Capacity is almost exclusively limited by personnel resources, but the capacity of personnel is rarely sufficiently analyzed. This is due to insufficient management tools and results in an inability to manage operations according to its constrained resources. Once resource constraints have been identified and quantified, the means for increasing capacity of bottlenecks are subject to improvements of technical and/or allocative efficiency. Here the benefits and potential of OM are significant. The study shows that there may be significant room for improvement of both technical and allocative efficiency in many areas of health care. Excessive focus is placed on the efficient management of non-constrained resources for which information is more readily available. This is likely to result in optimisation of non-constrained resources, which may be synonymous to sub-optimisation. Maximizing the use of non-constrained resources may impose new resource constraints. Economic efficiency depends on technical and allocative efficiency. Thus, improvements of technical and allocative efficiency are highly likely to render improvements of economic efficiency. On the regional level, economic efficiency improvement potential is likely to be subject to significant resource reallocation efforts. This study highlights the importance of maintaining a throughput- or process-oriented management mindset as opposed to mere focus on costs. Nevertheless, the importance of a more comprehensive state of analysis, which combines process and financial information, is strongly advocated

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Fast and Accurate Nanoparticle Characterization Using Deep-Learning-Enhanced Off-Axis Holography

Characterization of suspended nanoparticles in their native environment plays a central role in a wide range of fields, from medical diagnostics and nanoparticleenhanced drug delivery to nanosafety and environmental nanopollution assessment. Standard optical approaches for nanoparticle sizing assess the size via the diffusion constant and, as a consequence, require long trajectories and that the medium has a known and uniform viscosity. However, in most biological applications, only short trajectories are available, while simultaneously, the medium viscosity is unknown and tends to display spatiotemporal variations. In this work, we demonstrate a label-free method to quantify not only size but also refractive index of individual subwavelength particles using 2 orders of magnitude shorter trajectories than required by standard methods and without prior knowledge about the physicochemical properties of the medium. We achieved this by developing a weighted average convolutional neural network to analyze holographic images of single particles, which was successfully applied to distinguish and quantify both size and refractive index of subwavelength silica andpolystyrene particles without prior knowledge of solute viscosity or refractive index. We further demonstrate how these features make it possible to temporally resolve aggregation dynamics of 31 nm polystyrene nanoparticles, revealing previously unobserved time-resolved dynamics of the monomer number and fractal dimension of individual subwavelength aggregates