3D Printing of Bioglass-TCP Scaffolds: Biological and Mechanical Property Evolution

Primary Author: Arjak Bhattacharjee

Faculty Sponsor: Susmita Bose

Primary College/Unit: Voiland College of Engineering and Architecture

Category: Engineering and Environmental Science

Campus: Pullman

Abstract:

Primary Author: Arjak Bhattacharjee

Faculty Sponsor: Susmita Bose

Primary College/Unit: Voiland College of Engineering and Architecture

Category: Engineering & Environmental Science

Campus: Pullman

Abstract:

The objective of this study is to prepare 3D printed cytocompatible bioglass-TCP scaffolds with an optimum combination of porosity gradient and mechanical properties. Bioactive glasses (bioglass) are an excellent candidate for bone tissue engineering applications because of their excellent biological response and high dissolution rate. Tricalcium phosphate (TCP) are used for craniomaxillofacial applications owing to their chemical similarities with natural bone. Our results indicate that upto 5 wt.% bioglass addition in TCP enhances the compressive strength of the prepared scaffolds ~ 26.675 ± 5.45 MPa as compared to ~ 8.50 ± 0.830 MPa of control TCP. Simulated body fluid (SBF) dissolution study reveals that bioglass addition in TCP significantly improves the dissolution precipitation. Thus, this work affirms that 3D printed bioglass-tcp scaffolds can be a promising material for various biomedical applications. This poster will discuss fabrication of 3D printed bioglass-tcp scaffolds with optimum mechanical properties and controlled dissolution rate.

No Such Thing as Trash: A 3D-Printable Polymer Composite Composed of Oil-Extracted Spent Coffee Grounds and Polylactic Acid with Enhanced Impact Toughness

Primary Author: Yu-Chung Chang

Faculty Sponsor: Yuehe Lin

Primary College/Unit: Voiland College of Engineering and Architecture

Category: Engineering and Environmental Science

Campus: Pullman

Abstract:

Principal topic: As one of the most popular beverages in the world, a large amount of coffee wastes known as the spent coffee grounds (SCGs) is generated daily. It would be a waste if these SCGs is directly dumped to landfills. The advantage of SCGs it contains a lot of cellulose fibers that can be repurposed for new sustainable materials for a variety of applications.

Methods: In this study, we report a polylactic acid (PLA) composite filament with a high loading of oil-extracted spent coffee grounds (Ox-SCGs) up to 20% by weight and is three-dimensional (3D)-printable with a commercially available consumer-level 3D printer. The Ox-SCG-loaded PLA was found to be able to increase impact energy absorption. As a result, the PLA/Ox-SCG composite exhibited a 418.7% increase in toughness with a measure of 25.24 MJ/m3 at a 20 wt % Ox-SCG loading and only a 26% storage modulus reduction from the 100% PLA specimens at room temperature.

Results: The experimental results indicate that as a waste product from human consumptions and post biodiesel extraction, the Ox-SCG is proven to be a promising additive for composite property modification. Ox-SCG can not only increase the impact of toughness but also reduce the cost of overall 3D-printing materials. The applications of this composite materials are endless consider 3D printers are getting cheaper and the only limits are people’s imaginations

High Performance and Stability Solid Oxide Electrolysis Cell without Hydrogen as Safe Gas

Primary Author: Martinus Dewa

Faculty Sponsor: Su Ha

Primary College/Unit: Voiland College of Engineering and Architecture

Category: Engineering and Environmental Science

Campus: Pullman

Abstract:

Solid oxide electrolysis cell (SOEC) is a device that can transform CO2 and water into hydrogen (H2) and carbon monoxide (CO) using electricity through co-electrolysis process. H2 is often added during the SOEC operation as a safe gas to prevent the SOEC degradation. Removing H2 from the system can reduce the capital cost of the process. Nickel (Ni)/yttria-stabilized zirconia (YSZ) is a state-of-the-art electrode material for SOEC due to its good catalytic performance and electrical conductivity. However, many researchers claimed that it will rapidly deactivate under co-electrolysis without hydrogen since the Ni can be oxidized and becomes electrically non-conductive. CuFe2O4 has been recently investigated to substitute Ni/YSZ in SOECs since it has better stability under highly oxidizing condition such as co-electrolysis.

We fabricated the SOEC using both Nickel (Ni)/yttria-stabilized zirconia (YSZ) and CuFe2O4 by screen printing method. The electrochemical performance was measured under 1:1 ratio of CO2 and H2O at 800°C.

Our Ni/YSZ cell shows a decent performance of -400 mA/cm2 at 1.5 V and was stable after 24 h. However, Ni/YSZ requires activation by H2 during start up. CuFe2O4 cell can run without H2 activation and shows a slightly better performance of -475 mA/cm2 at 1.5 V. However, the stability was lower due to interface compatibility. Applying an additional La0.9Sr0.1Ga0.8Mg0.2O3 (LSGM) barrier layer successfully solved the stability issue, but electrochemical performance is compromised (-275 mA/cm2). Therefore, optimization of the design and fabrication method for the CuFe2O4 cell needs to be conducted to get both good performance and stability.

Humidity Controlled Micro Direct Ink Writing of Polymeric Bio-Ink for Drug Delivery and Bio-mimetic Tissue Synthesis

Primary Author: Kevin Estelle

Faculty Sponsor: Arda Gozen

Primary College/Unit: Voiland College of Engineering and Architecture

Category: Engineering and Environmental Science

Campus: Pullman

Abstract:

Principal topic

Bio-inks are biocompatible hydrogels and water-soluble polymers that are used to additively manufacture next-generation medical and pharmaceutical products. Through additive manufacturing, bio-inks loaded with biomaterials are extruded and assembled layer-by-layer to fabricate personalized artificial tissues and drug delivery vehicles. Success of such technologies relies on how precisely they mimic the complex microscale features of the native tissues, and there is a need to advance the current bio-printing technologies which do not possess this high manufacturing resolution. At lower size scales, the process suffers from rapid ink-drying and induced flow rate inconsistencies. This project can lead to more precise personalized drug delivery devices and artificial tissues.

Method

We propose a novel bio-printing implementation where the humidity at the end of the extrusion nozzle is controlled to overcome such issues. A co-axial nozzle design is implemented where the inner nozzle is used to extrude the bio-inks and the outer nozzle dispenses water saturated air. This system increases the relative humidity up to 100% and beyond at the deposition site. The controlled humidity effects are observed through changes in volume flow rate, height, width, aspect ratio, and layer-to-layer cohesion and associated sidewall morphology obtained via imaging of the printed structures.

Results/implications

It is shown that the deposited material volume, ink spreading, and layer-to-layer fusion is a strong function of the humidity level at the end of the nozzle. With increasing humidity, stacked layers are more fused, the stackability remains intact, and clogging is prevented, which all increase the printability of bio-inks.

Forest management and climate change effects on wildfire regimes of Cedar River Watershed

Primary Author: Rebecca Gustine

Faculty Sponsor: Jennifer Adam

Primary College/Unit: Voiland College of Engineering and Architecture

Category: Engineering and Environmental Science

Campus: Pullman

Abstract:

Fire exclusion, fire suppression, and climate change have altered wildfire regimes in the Western Cascades during past decades. Fire season is becoming longer and burned area in the Western Cascades are projected to increase 200-400% above contemporary levels by the end of the century. Such fire-regime changes can have cascading consequences for human and natural systems, including degradation of downstream water quality. Understanding the potential consequences of an altered fire regime will be necessary for managing forested watersheds to protect highly valued resources, especially high-quality drinking water. In this study, we apply the ecohydrologic model RHESSys, coupled with the fire spread model WMFire, to investigate how climate change and forest management techniques, such as stand thinning, can affect wildfire regimes in the Cedar River Watershed in western Washington, which provides drinking water for 1.4 million people in greater Seattle area. We run multiple simulations considering different climate change and forest management scenarios to assess the vulnerability of wildfire activity in this watershed and the efficacy of management practices to reduce fire impacts. Results show that both forest management and climate change alter the fire regime in the Cedar River watershed with fire suppression increasing the mean fire size while climate change increased the frequency of fires. By using processes-based model with factor-controlled simulation experiments, we can better inform the water management authorities, such as Seattle Public Utilities, on how to best mitigate the risk of wildfire-induced harm to drinking water.

Coordinated Voltage Control for Conservation Voltage Reduction in Power Distribution Systems

Primary Author: Rahul Jha

Faculty Sponsor: Anamika Dubey

Primary College/Unit: Voiland College of Engineering and Architecture

Category: Engineering and Environmental Science

Campus: Pullman

Abstract:

Principle Topic

An efficient operation of the distribution grid can be achieved using network-level optimization modeled as a distribution optimal power flow (D-OPF) problem. However, the variable power generation profiles of distributed energy resources (DERs) may render the optimal control decisions that are obtained in advance using D-OPF methods to sub-optimal.

Method

For conservation voltage reduction (CVR), a coordinated centralized and local control approach is developed that simultaneously achieves the network-level objective, while mitigating the impacts of DERs variability on optimal control set-points. The centralized controller solves a D-OPF problem for substation power reduction using a bi-level approach to control the system’s legacy voltage control devices (voltage regulator and capacitor banks) and smart inverters. A penalty successive linear programming (PSLP) approach is used to obtain a computationally tractable D-OPF model. Next, an adaptive volt-var droop control for the local control of smart inverters is proposed to minimize the voltage deviations (due to DERs variability) with respect to the centralized control set-points.

Results/Implications

The proposed coordinated control approach is validated using the modified IEEE 123-node test system which has four voltage regulators, four capacitor banks and twenty-six DERs.  The results show that the proposed control simultaneously reduces the power consumption from the substation to achieve CVR objective and voltage violations due to DERs variability.

Network Loss Analysis of Low-Voltage Low Power DC Microgrids for Rural Electrification

Primary Author: Rabia Khan

Faculty Sponsor: Noel Schulz

Primary College/Unit: Voiland College of Engineering and Architecture

Category: Engineering and Environmental Science

Campus: Pullman

Abstract:

Principal topic

The topic is “Network Loss Analysis of Low-Voltage Low Power DC Microgrids for Rural Electrification”. Millions of people around the globe are suffering  from energy poverty, particularly the inhabitants of Africa  and South-East Asia. Electrification through national grids is cost-prohibitive with limited power generation sources in the  third world countries. The low voltage, low-power islanded DC microgrids are a practical option for rural electrification.

Method

In this research work, the detailed network loss analysis of four different microgrid architectures is performed using the modified Newton-Raphson power flow for DC systems. These architectures include, 1) Centralized generation centralized storage (CGCS), 2) Centralized generation distributed storage (CGDS), 3) Distributed generation centralized storage (DGCS), and 4) Distributed generation distributed storage (DGDS), which are implemented with both radial and ring interconnection schemes using time-varying load demand and PV generation.

Results/implications

Comparative performance analysis of these architectures is done using the modified Newton-Raphson power flow method at different low-voltage levels and conductor sizes. The DGDS architecture with ring interconnection is the most efficient and reliable with an advantage of scalability, usage diversity, and mutual resource sharing capability. However, ring interconnection requires extra conductors, which increase the cost. So, a tradeoff between conductor size, voltage level, cost, interconnection scheme, and reliability is to be made while selecting the components for the microgrid architecture. The efficiency of systems is higher for conductors with lower AWG sizes but it is more expensive. So, trade-off between conductor size, voltage level, cost, interconnection scheme, and reliability is important.