Canon (Netherlands)

Liquid imbibition into coated paper is a complex process that strongly depends on the specific liquid and porous substrate of interest. Without coating, the timescales of capillary liquid uptake and paper swelling will be separated. However, a coupling between imbibition and swelling is expected in the presence of a coating. Understanding how liquid imbibes and how it reacts to different liquids is crucial to control liquid-substrate interactions. For the first time, a systematic study of the imbibition of water-glycerol mixtures into a complex layered porous medium like coated paper is performed using the Ultra Fast Imaging Nuclear Magnetic Resonance (UFI-NMR) method. This method allows to follow the in-situ liquid distributions over time. The effect of the coating is investigated by comparing the imbibition processes into paper with and without a coating. Liquid imbibition into coated paper is different from paper without a coating due to the flow resistance induced by the low permeability of the coating layer. It was concluded that liquid uptake and paper swelling are synchronized, and occurs locally at the tip of the liquid front. This is significantly different from liquid imbibition in uncoated paper, where liquid penetrates quickly and later swelling occurs more homogeneously throughout the paper. Moreover, it has been shown that both the imbibition and swelling speed are determined by viscosity. Consequently, Darcy's law for unsaturated flow still holds in this complex layered medium. This knowledge gets us a step closer to controlling liquid-media interactions in many different applications.

We aimed to evaluate the influence of contrast-enhanced dual-energy computed tomography (CE-DECT) in detecting and differentiating rheumatic joint diseases of the hand. In this prospective study, patients with suspected arthritis of the hand were investigated consecutively alongside the standard clinical procedure. CE-DECT with sequential rotations was performed in all patients before and 3-minutes after weight-adapted contrast agent application. Reconstructions included two-material decomposition for tophus imaging, virtual noncalcium for bone marrow edema, and CT subtraction for soft-tissue inflammation. All postprocessed images and original CT reconstructions were rated by two radiologists in consensus to generate an imaging diagnosis. Imaging findings in CE-DECT were juxtaposed with the initial and final evaluations by referring rheumatologists. This evaluation focused on surrogate performance criteria, emphasizing the added diagnostic value of CE-DECT in detecting specific imaging biomarkers associated with various arthritic pathologies. A subsequent survey assessed CE-DECT's diagnostic utility and impact on patient management, rated on a 1 to 10 scale. Descriptive statistics were employed. Overall, 136 patients were included in the analysis. In 119 patients (87.5%), the CE-DECT findings agreed with the final diagnosis. In 67 patients (49.2%), the diagnosis was changed following CE-DECT. Rheumatologists rated CE-DECT's diagnostic utility at a mean ± SD of 8.5 ± 2.1 and its contribution to patient management at 8.4 ± 1.8. CE-DECT showed high value for diagnosis and management of patients with suspected inflammatory arthritis. Its diverse diagnostic capabilities suggest that it can develop an important addition to current clinical workup pathways.

Administration of pulmonary surfactant is crucial for the treatment of respiratory distress syndrome (RDS) in preterm infants. The aim of this study is to evaluate the potential of Curosurf atomization via the Endosurf device, a recently developed spray technology, as a promising approach for surfactant delivery in infants with RDS. A comprehensive analysis was performed to evaluate the physicochemical properties of atomized Curosurf, including its surface tension and rheology. The size distribution of Curosurf vesicles was also investigated. An ex vivo respiratory model based on rabbit lungs breathing through an instrumented hypobaric chamber representing the thorax of a preterm infant was developed to provide proof of concept for regional aerosol deposition of atomized Curosurf. The atomization of Curosurf with the innovative Endosurf device did not significantly alter surface tension, but reduced vesicle size and promoted homogeneous distribution of Curosurf in the lungs. Rheological measurements showed the viscoelastic complexity of atomized Curosurf. This preliminary study confirmed the promising potential of Curosurf atomization via the Endosurf device for the distribution of surfactant in the lungs of infants with RDS. These advances could help to improve the treatment of RDS in preterm infants and offer new perspectives for healthcare professionals and affected families.

BackgroundDual-energy computed tomography (DECT) is useful for detecting gouty tophi. While iodinated contrast media (ICM) might enhance the detection of monosodium urate crystals (MSU), higher iodine concentrations hamper their detection. Calculating virtual noncontrast (VNC) images might improve the detection of enhancing tophi. The aim of this study was to evaluate MSU detection with VNC images from DECT acquisitions in phantoms, compared against the results with standard DECT reconstructions.MethodsA grid-like and a biophantom with 25 suspensions containing different concentrations of ICM (0 to 2%) and MSU (0 to 50%) were scanned with sequential single-source DECT using an ascending order of tube current time product at 80 kVp (16.5–220 mAs) and 135 kVp (2.75–19.25 mAs). VNC images were equivalently reconstructed at 80 and 135 kVp. Two-material decomposition analysis for MSU detection was applied for the VNC and conventional CT images. MSU detection and attenuation values were compared in both modalities.ResultsFor 0, 0.25, 0.5, 1, and 2% ICM, the average detection indices (DIs) for all MSU concentrations (35–50%) with VNC postprocessing were respectively 25.2, 36.6, 30.9, 38.9, and 45.8% for the grid phantom scans and 11.7, 9.4, 5.5, 24.0, and 25.0% for the porcine phantom scans. In the conventional CT image group, the average DIs were respectively 35.4, 54.3, 45.4, 1.0, and 0.0% for the grid phantom and 19.4, 17.9, 3.0, 0.0, and 0.0% for the porcine phantom scans.ConclusionsVNC effectively reduces the suppression of information caused by high concentrations of ICM, thereby improving the detection of MSU.Relevance statementContrast-enhanced DECT alone may suffice for diagnosing gout without a native acquisition.Key points• Highly concentrated contrast media hinders monosodium urate crystal detection in CT imaging• Virtual noncontrast imaging redetects monosodium urate crystals in high-iodinated contrast media concentrations.• Contrast-enhanced DECT alone may suffice for diagnosing gout without a native acquisition.Graphical

Inkjet printing inks frequently contain polar liquids of low volatility such as glycerol or poly(ethylene glycols) in addition to the main solvent water. The deposition of these liquids on paper sheets induces swelling of the cellulose fibers, which leads to an overall, anisotropic deformation of the sheet. We characterized the corresponding strain components by means of a grid projection method and white light interferometry. For pure water, most of the hydroexpansion strain vanishes again after drying is complete. However, for aqueous solutions of non-volatile co-solvents, a large fraction of the deformation persists after the water has evaporated. Because swelling occurs only after liquid enters the cellulose fibers, monitoring the dynamics of expansion provides insight into the pore-fiber distribution of co-solvents. The corresponding timescales of pore-fiber transport strongly depend on the co-solvent concentration, as a sufficient quantity of water is needed to plasticize the fiber walls.

A new tube voltage-switching dual-energy (DE) CT system using a novel deep-learning based reconstruction process has been introduced. Characterizing the performance of this DE approach can help demonstrate its benefits and potential drawbacks. To evaluate the technical performance of a novel DECT system and compare it to that of standard single-kV CT and a rotate/rotate DECT, for abdominal imaging. DE and single-kV images of four different phantoms were acquired on a kV-switching DECT system, and on a rotate/rotate DECT. The dose for the acquisitions of each phantom was set to that selected for the kV-switching DE mode by the automatic tube current modulation (ATCM) at manufacturer-recommended settings. The dose that the ATCM would have selected in single-kV mode was also recorded. Virtual monochromatic images (VMIs) from 40 to 130keV, as well as iodine maps, were reconstructed from the DE data. Single-kV images, acquired at 120kV, were reconstructed using body hybrid iterative reconstruction. All reconstructions were made at 0.5mm section thickness. Task transfer functions (TTFs) were determined for a Teflon and LDPE rod. Noise magnitude (SD), and noise power spectrum (NPS) were calculated using 240 and 320mm diameter water phantoms. Iodine quantification accuracy and contrast-to-noise ratios (CNRs) relative to water for 2, 5, 10, and 15mg I/ml were determined using a multi-energy CT (MECT) phantom. Low-contrast visibility was determined and the presence of beam-hardening artifacts and inhomogeneities were evaluated. The TTFs of the kV-switching DE VMIs were higher than that of the single-kV images for Teflon (20% TTF: 6.8 lp/cm at 40keV, 6.2 lp/cm for single-kV), while for LDPE the DE TTFs at 70keV and above were equivalent or higher than the single-kV TTF. All TTFs of the kV-switching DECT were higher than for the rotate/rotate DECT. The SD was lowest in the 70keV VMI (12.0 HU), which was lower than that of single-kV (18.3 HU). The average NPS frequency varied between 2.3 lp/cm and 4.2 lp/cm for the kV-switching VMIs and was 2.2 lp/cm for single-kV. The error in iodine quantification was at maximum 1mg I/ml (at 5mg I/ml). The highest CNR for all iodine concentrations was at 60keV, 2.5 times higher than the CNR for single-kV. At 70-90keV, the number of visible low contrast objects was comparable to that in single-kV, while other VMIs showed fewer objects. At manufacturer-recommended ATCM settings, the CTDIvol for the DE acquisitions of the water and MECT phantoms were 12.6 and 15.4 mGy, respectively, and higher than that for single-kV. The 70keV VMI had less severe beam hardening artifacts than single-kV images. Hyper- and hypo-dense blotches may appear in VMIs when object attenuation exceeds manufacturer recommended limits. At manufacturer-recommended ATCM settings for abdominal imaging, this DE implementation results in higher CTDIvol compared to single-kV acquisitions. However, it can create sharper, lower noise VMIs with up to 2.5 times higher iodine CNR compared to single-kV images acquired at the same dose.

HypothesisThermal Marangoni flow in evaporating sessile water droplets is much weaker in experiments than predicted theoretically. Often this is attributed to surfactant contamination, but there have not been any in-depth analyses that consider the full fluid and surfactant dynamics. It is expected that more insight into this problem can be gained by using numerical models to analyze the interplay between thermal Marangoni flow and surfactant dynamics in terms of dimensionless parameters. SimulationsTwo numerical models are implemented: one dynamic model based on lubrication theory and one quasi-stationary model, that allows for arbitrary contact angles. FindingsIt is found that insoluble surfactants can suppress the thermal Marangoni flow if their concentration is sufficiently large and evaporation and diffusion are sufficiently slow. Soluble surfactants, however, either reduce or increase the interfacial velocity, depending on their sorption kinetics. Furthermore, insoluble surfactant concentrations that cause an order 0.1% surface tension reduction are sufficient to reduce the spatially averaged tangential flow velocity at the interface by a factor 100. For larger contact angles and smaller droplets this required concentration is larger (typically <1% surface tension reduction). The numerical models are mutually validated by comparing their results in cases where both are valid.

Microbubbles entrained in a piezo-driven drop-on-demand printhead disturb the acoustics of the microfluidic ink channel and, thereby, the jetting behavior. Here, the resonance behavior of an ink channel as a function of the microbubble size and number of bubbles is studied through theoretical modeling and experiments. The system is modeled as a set of two coupled harmonic oscillators: one corresponds to the compliant ink channel and the other corresponds to the microbubble. The predicted and measured eigenfrequencies are in excellent agreement. It was found that the resonance frequency is independent of the bubble size as long as the compliance of the bubble dominates over that of the piezo actuator. An accurate description of the eigenfrequency of the coupled system requires the inclusion of the increased inertance of the entrained microbubble due to confinement. It is shown that the inertance of a confined bubble can be accurately obtained by using a simple potential flow approach. The model is further validated by the excellent agreement between the modeled and measured microbubble resonance curves. The present work, therefore, provides physical insight into the coupled dynamics of a compliant ink channel with an entrained microbubble.

Long and slender liquid filaments are produced during inkjet printing, which can subsequently either retract to form a single droplet, or break up to form a primary droplet and one or more satellite droplets. These satellite droplets are undesirable since they degrade the quality and reproducibility of the print, and lead to contamination within the enclosure of the print device. Existing strategies for the suppression of satellite droplet formation include, among others, adding viscoelasticity to the ink. In the present work, we aim to improve the understanding of the role of viscoelasticity in suppressing satellite droplets in inkjet printing. We demonstrate that very dilute viscoelastic aqueous solutions ($\text {concentrations} \sim 0.003\,\%$ wt. polyethylene oxide, corresponding to nozzle Deborah number$De_{n}\sim 3$) can suppress satellite droplet formation. Furthermore, we show that, for a given driving condition, upper and lower bounds of polymer concentration exist, within which satellite droplets are suppressed. Satellite droplets are formed at concentrations below the lower bound, while jetting ceases for concentrations above the upper bound (for fixed driving conditions). Moreover, we observe that, with concentrations in between the two bounds, the filaments retract at velocities larger than the corresponding Taylor–Culick velocity for the Newtonian case. We show that this enhanced retraction velocity can be attributed to the elastic tension due to polymer stretching, which builds up during the initial jetting phase. These results shed some light on the complex interplay between inertia, capillarity and viscoelasticity for retracting liquid filaments, which is important for the stability and quality of inkjet printing of polymer solutions.