Stiffening while drying

We present two models for the drying of waterborne paints, which consist of non-volatile latex particles suspended in water. One model considers the water and latex density in a layer as a function of time. Water evaporation at the surface represents the drying. This model results in a one-dimensional free boundary problem, which is solved numerically. Extensions to the model are given that describe the stiffening of the paint. A second model is a particle based dynamical simulation where latex particles form a network through which water particles move. A thin slab of the suspension in a three-dimensional box is studied. Water particles escaping the slab at the surface represent the drying, progressing network formation the stiffening of the paint. Both models allow for validation with material properties as determined experimentally on real coatings

AC field effect flow control of EOF in complex microfluidic systems with integrated electrodes

In this work, we demonstrate that positive net flow can be induced and controlled with relatively low potential due to the parallel alignment of the integrated channel electrodes. Therefore, we present a novel method to exquisitely control Electro Osmotic Flow (EOF) by using integrated electrodes fabricated beneath a meandering channel geometry (Figure 1). Equation 1 describes EOF velocity for AC-driven flow, where εo and εr respectively are the permittivity of vacuum and that of water, ζ the zeta potential at the solid liquid interface, η the viscosity, Ex the electric field

Predictive Uncertainty through Quantization

High-risk domains require reliable confidence estimates from predictive models. Deep latent variable models provide these, but suffer from the rigid variational distributions used for tractable inference, which err on the side of overconfidence. We propose Stochastic Quantized Activation Distributions (SQUAD), which imposes a flexible yet tractable distribution over discretized latent variables. The proposed method is scalable, self-normalizing and sample efficient. We demonstrate that the model fully utilizes the flexible distribution, learns interesting non-linearities, and provides predictive uncertainty of competitive quality

Improving Diagnosis and Treatment of Staphylococcus aureus Infections

__Abstract__ Staphylococcus aureus is an opportunistic pathogen that causes a variety of infections, ranging from mild skin infections like furuncles and impetigo, to severe, lifethreatening infections including endocarditis, osteomyelitis and pneumonia. Invasive infections are frequently associated with S. aureus bacteremia. Despite antibiotic treatment, the infection-related mortality rate in patients with S. aureus bacteremia is still 17%

Exploitation of a pH-sensitive hydrogel for CO2 detection

In this paper is described how hydrogel is exploited as sensor material for the \ud detection of carbon dioxide (CO2). A pH-sensitive hydrogel disc, which swells and deswells in response to pH changes, was clamped between a pressure sensor membrane and a porous metal screen together with a bicarbonate solution. Bicarbonate reacts with CO2 resulting in a pH change. The enclosed hydrogel will generate pressure as a response to the pH change. This pressure is a measure for the partial pressure of CO2. The main advantage of this sensor principle is the lack of a reference electrode as required for potentiometric sensors

A micro CO2 gas sensor based on sensing of pH-sensitive hydrogel swelling by means of a pressure sensor

In this paper a sensor is presented for the detection of carbon dioxide gas inside the stomach in order to diagnose gastrointestinal ischemia. The operational principle of the sensor is measuring the CO/sub 2/ induced pressure generation of a confined pH-sensitive hydrogel by means of a micro pressure sensor. The sensor is capable of measuring CO/sub 2/ with a response time between 2 and 4 minutes and a maximum pressure of 0.29/spl times/10/sup 5/ Pa at 20 kPa CO/sub 2/. The sensor is able to resist up to 1 M HCl acid as can be present inside the stomach. The results are very promising for real application and clinical trials are planned

Hydrodynamic resistance of concentration polarization boundary layers in ultrafiltration

The influence of concentration polarization on the permeate flux in the ultrafiltration of aqueous Dextran T70 solutions can be described by (i) the osmotic pressure model and (ii) the boundary layer resistance model. In the latter model the hydrodynamic resistance of the non-gelled boundary layer is computed using permeability data of the Dextran molecules obtained by sedimentation experiments. It is shown both in theory and experiment that the two models are equivalent

Chemically driven switches for online detection of pH changes in microfluidic devices

The internal walls of microfabricated fluidic channels were functionalized with a selfassembled monolayer of Rhodamine B lactam. This molecule has the capability to interconvert between its open fluorescent amide form and the closed non-fluorescent lactam form upon changes of the pH conditions. The interconversion (switch) between the two reversible forms is achieved by addition of an acid or a base and is consistent with a reaction mechanism of the first order. This paper describes the online observation of such fluorescent switch covalently anchored to the channel and proposes this method as a possible sensor for the monitoring of pH changes in microreactors

Large deviations for ideal quantum systems

We consider a general d-dimensional quantum system of non-interacting particles, with suitable statistics, in a very large (formally infinite) container. We prove that, in equilibrium, the fluctuations in the density of particles in a subdomain of the container are described by a large deviation function related to the pressure of the system. That is, untypical densities occur with a probability exponentially small in the volume of the subdomain, with the coefficient in the exponent given by the appropriate thermodynamic potential. Furthermore, small fluctuations satisfy the central limit theorem.Comment: 28 pages, LaTeX 2