Emerging 3D printing technologies are enabling the rapid fabrication of complex designs with favorable properties such as mechanically efficient lattices for biomedical applications. However, there is a lack of biocompatible materials suitable for printing complex lattices constructed from beam-based unit cells. Here, we investigate the design and mechanics of biocompatible lattices fabricated with cost-effective stereolithography. Mechanical testing experiments include material characterization, lattices rescaled with differing unit cell numbers, topology alterations, and hierarchy. Lattices were consistently printed with 5% to 10% lower porosity than intended. Elastic moduli for 70% porous body-centered cube topologies ranged from 360 MPa to 135 MPa, with lattices having decreased elastic moduli as unit cell number increased. Elastic moduli ranged from 101 MPa to 260 MPa based on unit cell topology, with increased elastic moduli when a greater proportion of beams were aligned with the loading direction. Hierarchy provided large pores for improved nutrient transport and minimally decreased lattice elastic moduli for a fabricated tissue scaffold lattice with 7.72 kN/mm stiffness that is suitable for bone fusion. Results demonstrate the mechanical feasibility of biocompatible stereolithography and provide a basis for future investigations of lattice building blocks for diverse 3D printed designs.

The geometry of the tibial plateau and the femoral condyles are emerging as key parameters to be studied as anterior cruciate ligament (ACL) injury risk factors. In this paper, we study the role of curved profile of the medial compartment of the tibia in a sagittal plane as a critical risk factor for the anterior cruciate ligament (ACL) injuries. The curvature of the mid-medial compartment of Tibia in 40 uninjured controls (21 women and 19 men) and 44 anterior cruciate ligament-injured cases (23 women and 21 men) were measured using magnetic resonance images and in-house matlab programming. We hypothesized that the Individuals with a less curved profile in the medial compartment of the tibia are at increased risk of suffering an anterior cruciate ligament injury compared to those with larger curved profiles. Based on t-tests, we established that the uninjured controls had larger curvature (p<0.05) compared to the injured cases. Biomechanically speaking a larger curvature of the tibia could prevent excessive sliding movement of femur with respect to the tibia, and thus could reduce the ACL strain. We suggest that future studies are needed to confirm this relationship and to evaluate the potential role of this curved profile of tibia in the risk of ACL injury.

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Recent advances in exploration and energy extraction have been significant and occurred very quickly, greatly impacting the US economy. A major component of these advances is the electrical submersible pump (ESP), which targets high-volume energy extraction. Consequently, ESP testing system demands are increasing to new levels. Reliable and safe testing systems that provide quick, accurate, and repeatable results are highly desirable.A service company recently developed a highly accurate, reliable, and fast ESP testing system. The new, improved testing system incorporates a control valve coupled with an actuator, two electromagnetic flow meters, a variable frequency driver (VFD), and programmable logic controller (PLC) driven automation. API standards were strictly followed concerning flow, pressure, and torque measurements. A proprietary software package allows real-time communication with the PLC and helps operators to run tests and to post test results online. Finally, identified safety issues were mitigated, either by design or administrative methods, to help minimize their severity.The newly improved testing system helps reduce pump testing time by 75%. This new design is also modular, which helps to reduce transportation/installation costs and greatly simplifies installation.

A three dimensional (3D) Finite Element (FE) human knee joint model developed from magnetic resonance images (MRI) has been validated with the sets of experimental results in a normalized scale. The performance of the 3D FE knee joint model has been tested, simulating a physical experiment. The experiment provided the direct measurement of Anterior Cruciate Ligament (ACL) strains due to the forces of Quadricep Muscle Force (QMF) followed by Ground Reaction Force (GRF) at low knee flexion. Accurate and precise anatomy has been obtained from segmented MRI images. The ACL strain subject to the loading was calculated and analyzed compared with the measured data from the experimental tests. The study shows that the pre-activated ACL strain, which is measured before the application of GRF, increased nonlinearly with increasing QMF before landing. However, the total ACL strain, which is measured after both QMF and GRF applied, reaches out to the limited constant value (6%) instead of crossing the ACL failure value. These results suggest that the forces generated from QMF and GRF at low flexion may not bring ACL to a failure level as presented in the experimental tests. The results of the FE model fall into the standard deviations of the 22 cadaveric knees testing results, which represents the successful mechanical modeling of ACL and the surrounding structures of the human knee joint. The model may further be used to investigate the risks of the ACL injury.