Flexible Material Formulations for 3D Printing of Porous Beds with Applications in Bioprocess Engineering

Background: 3D printing is revolutionizing many industrial sectors and has the potential to enhance also the biotechnology and bioprocessing fields. Here, we propose a new flexible material formulation to 3D print support matrices with complex, perfectly ordered morphology and with tuneable properties to suit a range of applications in bioprocess engineering. Findings: Supports for packed-bed operations were fabricated using functional monomers as the key ingredients, enabling matrices with bespoke chemistry such as charged groups, chemical moieties for further functionalization, and hydrophobic/hydrophilic groups. Other ingredients, e.g. crosslinkers and porogens, provide the opportunity to further tune the mechanical properties of the supports and the morphology of their porous network. Through this approach, we fabricated and demonstrated the operation of Schoen gyroid columns with I) positive and negative charges for ion-exchange chromatography, II) enzyme bioreactors with immobilized trypsin to catalyse hydrolysis, and III) bacterial biofilms bioreactors for fuel desulfurization. Conclusions: This study demonstrates a simple, cost-effective and flexible fabrication of customized 3D printed supports for different biotechnology and bioengineering applications.

Self-healing efficiency study of thermoset-thermoplastic polymer material

This study is focused on exploring intrinsic self-healing polymer material development, where the inclusion of thermoplastic additives into thermoset polymer material as healing agents. Intrinsic self-healing thermoset-thermoplastic development is involving the material formulation of thermoset liquid resin (Poly Bisphenol A-co-epichlorohydrin) and thermoplastic (polycaprolactone). The material formulation ratio is up to 30% polycaprolactone with respect to thermoset weight. The mixture is heated and stirred to saturate at 80°C before the hardener is added. The mixture is cured and further finishing as Charpy impact test specimen. The specimen is fractured and absorbed impact energy property characterised through the Charpy impact test. The heat treatment is then performed to trigger the self-healing reaction in the polymer. The self-healing efficiency of the thermoset thermoplastic is investigated based on the absorbed impact energy before and after the heat treatment. The 20% or higher thermoplastic concentration in the polymer caused the polymer to possess high self-healing efficiency and faster healing time as compared to the low thermoplastic concentration polymer. However, the high concentration polymer has a disadvantage on the overall structural strength instead. On the contrary, 10% to 15% thermoplastic composition will result in lower and slower self-healing performance but higher initial structural strength.

A Novel Epoxy Resin Composition as a Lost Circulation Material: Formulation, Lab Testing and Field Execution

The novel resin composition described in this paper has been designed to treat moderate to severe losses. The resin composition comprises an epoxy resin and a chemical activator that undergo a polymerization reaction without any addition of water. The polymerization was designed to delay and successfully controlled to gel up and form the target resin composition after the fluid goes inside the wellbore. This is very important to avoid early setting of the fluid. The objective of this paper is to discuss the formulation of epoxy resin as a lost circulation material and also detail the lab testing and field execution. In this study, we used two different epoxy resins to study the development of the novel loss circulation material. One contains two epoxy groups and the other contains only one epoxy group. Two different chemical activators have been used in this study as well; each of them differs in the number of amine groups and geometry. The effect of these differences on the polymerization in terms of time and properties were investigated. In addition, the effect of the chemical activator concertation on the setting time of the resin composition was investigated to accomplish a controlled and a delayed polymerization. Also, the chemical conditions were evaluated to simulate a variety of downhole conditions to prove the effectiveness of this novel resin composition as a loss circulation treatment. The lab testing includes thickening time measurements. The novel resin composition is designed to have a controlled thickening time under a variety of downhole conditions. This is important to have an accurate placement of the fluid inside the wellbore; thus, avoiding an early setting of the fluid. We found that the thickening time of the resin composition can be controlled by mainly varying the concertation of the chemical activator. We found as well that changing the type of epoxy resin or chemical activator produce different gelling time and properties. We designed the loss circulation composition to provide a predictable and controlled pumping time. This novel resin composition can remain in a liquid phase from a few minutes to several hours based on the desired conditions. This is favorable in order to have an accurate placement of the fluid inside the wellbore over a predictable and controlled period of time. The final and target resin composition, will appear and gel as a solid thereby preventing loss circulation. The resin was pumped from the BHA in a single stage which helped mitigate and reduce the dynamic losses from 260 bbl./hr. to 200 bbl./hr. using only 25 bbls and eventually to zero.

The 3D/4D Printing Defects and Their Influence on the Functional Behavior of the Achieved Items from Renewable Compounds. (I)

The paper is part of a series in which the influence of the manufacturing defects on the functional behavior in biodegradation medium of some items obtained, both by 3D printing and by classical procedure (pressing), from an originaly renwable matrials based on polylatic acid will be presented. The first results regarding the correlation of the defects appeared at manufacturing into plates with the biodegradation behavior in an Aspergillus Niger(A.niger) medium, studied by SEM microscopy, are presented. These results demonstrated that the development of the A. Niger microorganism is related manly to the defects appeared at the melt processing of renewable polymeric material into finished product. A notable role in controlling the appearance of the manufacturing defects belongs both to the melt rheological properties which are responsible for the continuous or discontinuous flow and to the technical performance of the used equipement, 3D printer or classic hydraulic press. If the polymeric material melt has too high viscosity than the continuous flow is not possible and so the overlapped melt fronts are created which generate the voids formation, sometimes joined by small nano and/or micrometric channels. The rheological properties of the melts depend both on the material formulation and the seleted melt processing conditions.

A new 3D finite element-based approach for computing cell surface tractions assuming nonlinear conditions

Advances in methods for determining the forces exerted by cells while they migrate are essential for attempting to understand important pathological processes, such as cancer or angiogenesis, among others. Precise data from three-dimensional conditions are both difficult to obtain and manipulate. For this purpose, it is critical to develop workflows in which the experiments are closely linked to the subsequent computational postprocessing. The work presented here starts from a traction force microscopy (TFM) experiment carried out on microfluidic chips, and this experiment is automatically joined to an inverse problem solver that allows us to extract the traction forces exerted by the cell from the displacements of fluorescent beads embedded in the extracellular matrix (ECM). Therefore, both the reconstruction of the cell geometry and the recovery of the ECM displacements are used to generate the inputs for the resolution of the inverse problem. The inverse problem is solved iteratively by using the finite element method under the hypothesis of finite deformations and nonlinear material formulation. Finally, after mathematical postprocessing is performed, the traction forces on the surface of the cell in the undeformed configuration are obtained. Therefore, in this work, we demonstrate the robustness of our computational-based methodology by testing it under different conditions in an extreme theoretical load problem and then by applying it to a real case based on experimental results. In summary, we have developed a new procedure that adds value to existing methodologies for solving inverse problems in 3D, mainly by allowing for large deformations and not being restricted to any particular material formulation. In addition, it automatically bridges the gap between experimental images and mechanical computations.