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This work describes a novel rapid method to fabricate high-resolution paper-based microfluidic devices using wax-ink-based printing. This study demonstrates that both temperature and pressure are important knobs in controlling the device resolution. High-resolution lines and patterns were obtained by heating the paper asymmetrically from one side up to 110 °C while applying pressure up to 49 kPa. Starting with wax lines with an initial width of 130 μm, we achieve a thorough penetration through a 190 μm-thick paper with lateral spreading on the front as narrow as 90 μm. The role of temperature and pressure are systematically studied and compared with the prediction of the Lucas-Washburn equation. We found that the temperature dependence of spreading can be explained by the viscosity change of the wax, according to the Lucas-Washburn equation. The pressure dependence deviates from Lucas-Washburn behavior because of compression of the paper. An optimal condition for achieving full depth penetration of the wax yet minimizing lateral spreading is suggested after exploring various parameters including temperature, pressure, and paper type. These findings could lead to a rapid roll-to-roll fabrication of high-resolution paper-based diagnostic devices. [ABSTRACT FROM AUTHOR]

Friction between different papers, flexographic and laser prints were investigated experimentally and static (SCOF) and kinetic (KCOF) friction coefficients between paper and paper, paper and prints, prints and prints were determined. The dependence of the the SCOF and KCOF values on the paper PPS roughness, paper grammage and ink content on prints was investigated. The results showed that highest friction is between paper and prints and lowest is between two prints. It was found that SCOF and KCOF deacrease with pressure. Static friction coefficient increases with paper roughness and kinetic coefficient remains constant. [ABSTRACT FROM AUTHOR]

Abstract: This study explores the possibility of converting a self-supporting, randomly aligned, low impedance multi-wall carbon nanotube (MWCNT) paper into a resistive temperature measurement unit working at ambient pressure in air in the 25–70°C range. Thermosensitization was achieved by decorating the surface of the films with pyroelectric CsNO3 or LiNbO3 crystals. Assuming a linear temperature response, temperature coefficient of resistance values of −0.158%°C−1 and −0.246%°C−1 were calculated for CsNO3 and LiNbO3 doped films, respectively. The corresponding temperature measurement accuracies (2.2°C and 3.0°C) are acceptable for some applications but the precision of the temperature measurement needs to be improved. [Copyright &y& Elsevier]

Steam heating characteristics of wet paper are studied experimentally and numerically. Experimental results show that suction pressure enhances energy absorption in the wet paper and decreases temperature difference in the paper thickness direction, and effects of suction pressure strongly appear in the high-permeability paper. Experiments also indicate that the absorbed energy rate is decreased with increasing in the heating time. Temperature, moisture, and pressure distributions in the paper thickness direction are calculated from the numerical simulation model. From the numerical simulation it is found that increasing of the moisture content and thickness of the condensation region reduce the absorbed energy rate. [ABSTRACT FROM AUTHOR]

In this paper, we introduce a few notions of inverse topological pressure $({\tilde P}^-, P^-, P_- )$, defined in terms of backward orbits (prehistories) instead of forward orbits. This inverse topological pressure has some properties similar to the regular (forward) pressure but, in general, if the map is not a homeomorphism, they do not coincide. In fact, there are several ways to define inverse topological pressure; for instance, we show that the Bowen type definition coincides with the one using spanning sets. Then we consider the case of a holomorphic map $f:{\mathbb P}^2 {\mathbb C}\to {\mathbb P}^2 {\mathbb C}$ which is Axiom A and such that its critical set does not intersect a particular basic set of saddle type Λ. We will prove that, under a technical condition, the Hausdorff dimension of the intersection between the local stable manifold and the basic set is equal to ts, i.e. $HD (W^s_\delta (x)\cap \Lambda)=t^s$, for all points x belonging to Λ. Here ts represents the unique zero of the function t→P-(tϕs), with P- denoting the inverse topological pressure and $\phi^s(y):=\log|Df|_{E_y^s}$, y∈Λ. In general, $HD (W^s_\delta (x)\cap\Lambda)$ will be estimated above by ts and below by $t^s_-$, where $t^s_-$ is the unique zero of the map t→P_(tϕs). As a corollary we obtain that, if the stable dimension is non-zero, then Λ must be a non-Jordan curve, and also, if f|Λ happens to be a homeomorphism (like in the examples from [13]), then the stable dimension cannot be zero. [ABSTRACT FROM AUTHOR]

Rolls of films and paper are routinely stored under varying conditions before being unwound into downstream operations. During storage, interlayer pressures can change relative to the pressures generated during winding. These changes can lead to problems such as film/paper blocking (increased interlayer pressure) and roll shifting/cinching (decreased interlayer pressure). To study the storage effect, a nonlinear wound roll stress model including air entrainment is first developed and applied to predict the in-roll stresses during film/paper winding. Thereafter, a thermal stress model is used to study the temperature effect on wound roll stresses. Key inputs to the models are the stack modulus, contact clearance, and air film reference clearance. A method is developed to measure these key model inputs. Results of a parametric study show that among the processing conditions, storage temperature and thermal expansion coefficients of the core and the film/paper are key factors that affect in-roll stresses during storage. Limitations of the models will also be discussed along with recommendations for future modeling development. [ABSTRACT FROM AUTHOR]