The effect of droplet ejection frequency on the dimensions of inkjet-etched micro-via holes in poly4(-vinyl phenol) thin films

This article was published in the Journal of Physics D: Applied Physics [© IOP Publishing Ltd] and the definitive version is available at: http://dx.doi.org/10.1088/0022-3727/45/12/125303The relationship between the size of inkjet-etched via-holes produced in poly4(-vinyl phenol) thin films and the number of ethanol drops dispensed was established for a range of droplet ejection frequencies. The physical mechanism underlying this relationship is proposed and the dependence of the development of via-hole dimensions on the droplet ejection frequency is believed to be attributable to the extent of evaporation of the solvent between two consecutive drop dispenses. The results indicate complete penetration of the via-holes through the polymer layer when produced at low droplet ejection frequencies. Electroplating was used to deposit Cu into the created holes to further confirm the absence of polymer residue at low frequencies. A threshold frequency, under which no via-hole enlargement occurs, has been found. The study systematically focuses on the influence of droplet ejection frequency on the size of the inkjet-etched via-holes versus the number of droplets used in poly4(-vinyl phenol) dielectric thin films for printed electronics application

Spreading behavior of single and multiple drops

This paper describes experimental and numerical work relevant to the impact of single and multiple drops onto various solid substrates. The experimental methods are based on visualization techniques and the single drop spreading transients are obtained using the variational principle and a commercial numerical code. The collision of two drops is then considered and the results lead to a simple model able to describe the axisymmetric collision of drops. The extension of the model to other forms of coalescence is also discussed

Printing of dye and pigment based aqueous inks onto porous substrates

In this article, the dynamics of droplet impingement and absorption into microporous materials for pigment based aqueous inks and dye based aqueous inks are compared. For dye based inks it was shown earlier that three main phases could be resolved: inertial spreading, absorption, and evaporation of the liquid, leading to the final equilibrium condition on which the typical customer is evaluating the image quality. For the inertial spreading phase it could be shown that the spreading behavior is largely determined by the hydrodynamic properties, and is easily amenable to dimensionless analysis. The absorption phase could be well described by a capillary wicking process according to imbibition models. Evaporation is the slowest process only being finalized after many seconds. These results are now compared with droplet impingement and absorption of pigment based inks on microporous receivers. It is shown that these inks behave totally differently from dye based inks. Immediately after impingement and initial spreading the pigment particles start to coagulate on the surface of the microporous layer, creating a filter cake limiting the passage of carrier liquid. As a result much longer absorption times are observed and the equilibrium dot stays on top of the microporous layer. Most polymer stabilizers in the pigment based inks create a colored polymer layer having polymeric blend characteristics limiting considerably the penetration of water compared to the capillary wicking process. The capillary imbibition models are not valid any more because now the build-up of the filter cake changes not only the receding contact angle but also introduces a diffusion process changing as a function of time during the drying of the wet ink

A mechanism of the penetration limit for producing holes in poly(4-vinyl phenol) films by inkjet etching

This is an author-created, un-copyedited version of an article published in Journal of Physics D: Applied Physics. IOP Publishing Ltd is not responsible for any errors or omissions in this version of the manuscript or any version derived from it. The Version of Record is available online at http://dx.doi.org/10.1088/0022-3727/48/45/455501.A penetration limit has been experimentally demonstrated for inkjet etching of holes in thin polymer layers. A mechanism combining the competing coffee ring flow, polymer dissolution and diffusion into the solvent drop, and the interaction between the contact line during evaporation and the softened deformable polymer, is proposed to explain the existence of such a penetration limit. The height-averaged velocity of the coffee ring flow within the evaporating sessile drop is calculated during the initial stage of this etching process when the spherical cap geometry assumption is valid. This is compared with the diffusion velocity of the disentangled polymer into the solvent. The two competing flows are used to elucidate why a hole could be formed initially. The complex wetting dynamics of the receding contact line is included to explain the via hole profile evolution in the later stage of the etching process and the existence of a penetration limit. These two stages are differentiated by the drop volume with respect to the volume of the via hole produced by the preceding drop. The competition between the coffee ring flow transferring polymer away from the central region and the polymer diffusion within the solvent drop is postulated to contribute to either via hole formation or a penetration limit, depending on which one of the two processes is dominant within the solvent evaporation time scale

Food intake and darunavir plasma concentrations in people living with HIV in an outpatient setting

AIMS Patients receiving darunavir are advised to take it concomitantly with food. The objectives of the present cross-sectional study were to evaluate the actual concomitant food intake of patients visiting an HIV outpatient clinic. METHODS Sixty participants treated with darunavir/ritonavir once daily were subjected to a food recall questionnaire concerning their last concomitant food intake with darunavir. Darunavir trough concentrations were calculated. RESULTS The median food intake was 507 (0-2707) kcal; protein intake, 20 (0-221)g; carbohydrate intake, 62 (0-267)g; fat intake: 14 (0-143)g; and dietary fibre: 4 (0-30)g. Twenty-five patients (42%) ingested their drug with between-meal snacks. No relationship was found between food intake and trough concentrations. CONCLUSIONS Clear advice on the optimal caloric intake is needed, to avoid high caloric intake in patients who already have an increased risk of cardiovascular disease due to their HIV infection

Shared species of crocodilian trypanosomes carried by tabanid flies in Africa and South America, including the description of a new species from caimans, Trypanosoma kaiowa n. sp.

Abstract Background The genus Trypanosoma Gruby, 1843 is constituted by terrestrial and aquatic phylogenetic lineages both harboring understudied trypanosomes from reptiles including an increasing diversity of crocodilian trypanosomes. Trypanosoma clandestinus Teixeira & Camargo, 2016 of the aquatic lineage is transmitted by leeches to caimans. Trypanosoma grayi Novy, 1906 of the terrestrial lineage is transmitted by tsetse flies to crocodiles in Africa, but the vectors of Neotropical caiman trypanosomes nested in this lineage remain unknown. Results Our phylogenetic analyses uncovered crocodilian trypanosomes in tabanids from South America and Africa, and trypanosomes other than T. grayi in tsetse flies. All trypanosomes found in tabanids clustered in the crocodilian clade (terrestrial lineage) forming six clades: Grayi (African trypanosomes from crocodiles and tsetse flies); Ralphi (trypanosomes from caimans, African and Brazilian tabanids and tsetse flies); Terena (caimans); Cay03 (caimans and Brazilian tabanids); and two new clades, Tab01 (Brazilian tabanid and tsetse flies) and Kaiowa. The clade Kaiowa comprises Trypanosoma kaiowa n. sp. and trypanosomes from African and Brazilian tabanids, caimans, tsetse flies and the African dwarf crocodile. Trypanosoma kaiowa n. sp. heavily colonises tabanid guts and differs remarkably in morphology from other caiman trypanosomes. This species multiplied predominantly as promastigotes on log-phase cultures showing scarce epimastigotes and exhibited very long flagellates in old cultures. Analyses of growth behavior revealed that insect cells allow the intracellular development of Trypanosoma kaiowa n. sp. Conclusions Prior to this description of Trypanosoma kaiowa n. sp., no crocodilian trypanosome parasitic in tabanid flies had been cultured, morphologically examined by light, scanning and transmission microscopy, and phylogenetically compared with other crocodilian trypanosomes. Additionally, trypanosomes thought to be restricted to caimans were identified in Brazilian and African tabanids, tsetse flies and the dwarf crocodile. Similar repertoires of trypanosomes found in South American caimans, African crocodiles and tabanids from both continents support the recent diversification of these transcontinental trypanosomes. Our findings are consistent with trypanosome host-switching likely mediated by tabanid flies between caimans and transoceanic migrant crocodiles co-inhabiting South American wetlands at the Miocene