Lignocellulosic biomass pretreatment: Industrial oriented high-solid twin-screw extrusion method to improve biogas production from forestry biomass resources.

Forestry lignocellulosic waste is an important, largely untapped source of biomass for producing clean energy. In this study, a high-solids twin-screw extrusion approach is developed as a novel pretreatment method to effectively increase the biogas production rate to better fit commercial requirements. Multiple screw designs are progressively introduced with increasingly intensified mechanical shear. The experiments also looked at the impact of feed solids content and several cost-effective processing aids along with these screw designs. Various characterization methods were used to relate the physical state of the biomass based on its specific surface area and volatile fraction, to the rate of biomethane generation possible from a 14- and 31-day biomethane potential test. An increase in biomethane production over this period by up to 190% was possible with the optimal screw design compared to a benchmark sample. This is a promising finding for the industrialization of biomethane production from forestry lignocellulosic biomass.

Spatio-temporal interpolation and delineation of extreme heat events in California between 2017 and 2021.

Robust spatio-temporal delineation of extreme climate events and accurate identification of areas that are impacted by an event is a prerequisite for identifying population-level and health-related risks. In prior research, attributes such as temperature and humidity have often been linearly assigned to the population of the study unit from the closest weather station. This could result in inaccurate event delineation and biased assessment of extreme heat exposure. We have developed a spatio-temporal model to dynamically delineate boundaries for Extreme Heat Events (EHE) across space and over time, using a relative measure of Apparent Temperature (AT). Our surface interpolation approach offers a higher spatio-temporal resolution compared to the standard nearest-station (NS) assignment method. We show that the proposed approach can provide at least 80.8 percent improvement in identification of areas and populations impacted by EHEs. This improvement in average adjusts the misclassification of about one million Californians per day of an extreme event, who would be either unidentified or misidentified under EHEs between 2017 and 2021.

Development, processing and characterization of Polycaprolactone/Nano-Hydroxyapatite/Chitin-Nano-Whisker nanocomposite filaments for additive manufacturing of bone tissue scaffolds.

This paper focuses on utilizing the Fused Deposition Modeling (FDM) to manufacture Polycaprolactone/Nano-Hydroxyapatite/Chitin-Nano-Whisker nanocomposite scaffolds and their subsequent characterization for biomedical applications. FDM nanocomposite filaments were manufactured in multiple nanocomposite formulations of Polycaprolactone/Nano-Hydroxyapatite (nHA), Polycaprolactone/Chitin-Nano-Whisker (CNW), and Polycaprolactone/nHA/CNW using a green method. The FDM processing conditions were optimized using Taguchi orthogonal array method. The mechanical, biodegradation, and biocompatibility properties of the bone tissue scaffolds were assessed. A preosteoblast mouse bone cell line was used for cell proliferation and attachment assays. The results indicated that CNW content in the filaments slightly increases the mechanical properties of the 3D printed parts, and the nanocomposite with 3% CNW content exhibited significant improvement in the cell proliferation and attachment properties of the scaffolds. The nHA content considerably improved the mechanical properties of the scaffolds. The nHA and CNW nanofillers increased the biodegradation rate of PCL. In general, considering all types of responses, a green manufactured nanocomposite of PCL/nHA/CNW can significantly increase the biological and mechanical properties of the 3D printed products for bone tissue scaffolds.

Effects of design, porosity and biodegradation on mechanical and morphological properties of additive-manufactured triply periodic minimal surface scaffolds.

The main aim of this paper is to assess the impacts of design, porosity, and biodegradation on the mechanical and morphological properties of triply periodic minimal surface (TPMS) scaffolds. The TPMS scaffolds were designed and manufactured with different porosities by using fused deposing modeling (FDM) technique. The biodegradation test on the scaffolds was performed for four and six months. The mechanical properties were assessed employing ASTM standard compression test and an in-situ mechanical testing stage. Microcomputed tomography (Micro-CT) technique was used to investigate detailed morphological properties of the scaffolds in 3D. Results indicate that the Schwarz-D scaffolds exhibit the highest compressive strength in lower porosity scaffolds but lose mechanical properties when the porosity was increased. On the contrary, Gyroid scaffolds maintain their strength as the porosity was increased. In addition, Gyroid scaffolds preserve a higher percentage of their compressive strength after six months of biodegradation. It was also observed that biodegradation phenomenon transformed the mechanical failure mode of the scaffolds from ductile to brittle. Morphological analysis of the scaffolds revealed detailed information, which support and clarify the observed variations in the mechanical properties.