Medial unicompartmental knee arthroplasty to patients with a ligamentous deficiency can cause biomechanically poor outcomes.

PURPOSE: The aims of this study were to investigate the biomechanical effects of the deficiency of the collateral ligament and cruciate ligament in medial unicompartmental knee arthroplasty in normal and varus knee patients using computational simulation. METHODS: Validated finite-element (FE) models for conditions of various cruciate and collateral ligament deficiencies were developed to evaluate the biomechanical effects of ligamentous deficiency in UKA for normal and varus knee patients. Contact stresses on the polyethylene (PE) insert, contact stresses on the lateral articular cartilage, and quadriceps force were analyzed under gait-loading conditions. RESULTS: Contact stresses on the PE insert and lateral articular cartilage as well as quadriceps force in a normal knee UKA FE model were increased in the order of anterior cruciate ligament (ACL) deficiency, medial collateral ligament (MCL) deficiency, lateral collateral ligament (LCL) deficiency, and posterior cruciate ligament (PCL) deficiency in the stance phase of gait cycle, as compared with those in the model without ligamentous deficiency. In two or more multiple ligamentous deficiencies, contact stresses on the PE insert and articular lateral cartilage and quadriceps force were significantly increased versus in the case of single-ligament deficiency. CONCLUSION: Poor outcomes of medial UKA in patients with ACL or MCL deficiency can be predicted. Care should be taken to extend the indications when performing medial UKA in patients with ligamentous deficiency, especially when varus knee with ACL or MCL deficiency is present.

Controlled mechanical buckling for origami-inspired construction of 3D microstructures in advanced materials.

Origami is a topic of rapidly growing interest in both the scientific and engineering research communities due to its promising potential in a broad range of applications. Previous assembly approaches of origami structures at the micro/nanoscale are constrained by the applicable classes of materials, topologies and/or capability of control over the transformation. Here, we introduce an approach that exploits controlled mechanical buckling for autonomic origami assembly of 3D structures across material classes from soft polymers to brittle inorganic semiconductors, and length scales from nanometers to centimeters. This approach relies on a spatial variation of thickness in the initial 2D structures as an effective strategy to produce engineered folding creases during the compressive buckling process. The elastic nature of the assembly scheme enables active, deterministic control over intermediate states in the 2D to 3D transformation in a continuous and reversible manner. Demonstrations include a broad set of 3D structures formed through unidirectional, bidirectional, and even hierarchical folding, with examples ranging from half cylindrical columns and fish scales, to cubic boxes, pyramids, starfish, paper fans, skew tooth structures, and to amusing system-level examples of soccer balls, model houses, cars, and multi-floor textured buildings.

Characteristics of fractionated drop-in liquid fuel of plastic wastes from a commercial pyrolysis plant.

Pyrolysis is a waste conversion technology to solve an increasing plastic waste issue worldwide. Waste plastic pyrolysis fuel from a commercial-scale pyrolysis plant (10 ton/day) was comprehensively investigated using distillation methods by separating the crude pyrolysis fuel to isolate the diesel-like pyrolysis fuel fraction (C9-C25 for fraction 2 + fraction 3, middle distillate). Other fractions were C5-C10 for the light distillate (fraction 1), and >C25 for the heavy distillate (fraction 4). The relationship between the fuel boiling point and liquid vapor temperature were found for designing a scaled-up oil separation process. The diesel grade pyrolysis fuel fraction comprised approximately 70-80% of the crude pyrolysis fuel, wherein it had values of 43-45 MJ/kg, 1-6 cSt, and 12-42 mgKOH/goil. Meanwhile, the elemental ratios of the crude pyrolysis oil improved to 0.1 for O/C and 1.9 for H/C after separation, close to petroleum fuels (0.0 O/C and 1.95 H/C). The highest relative chemical composition was the olefins (46% in fraction 1 and 41% in fraction 2), whereas the paraffin was approximately 15-20% in the light fraction. Finally, the potential CO2 reduction for the plastic waste-to-energy process was evaluated, revealing that a total of 0.26 tCO2/tonwaste of emissions could be avoided during the waste plastic pyrolysis process.

Arsenic treatment and power generation with a dual-chambered fuel cell with anionic and cationic membranes using NaHCO3 anolyte and HCl or NaCl catholyte.

Dual-chambered fuel cells with an iron anode and an air-carbon cathode separated by an ion exchange membranes have been used to treat arsenate during power production. To select an effective catholyte, the dual-chambered fuel cell consisted 90 mL of 0.1 M HCl or 0.5 M NaCl as the catholyte and 1 L of 0.1 M NaHCO3 as the anolyte at an initial pH 5. The 0.1 M HCl was an effective catholyte, with which 1 ppm arsenate in 1 L of anolyte was reduced to 5 ppb in 1 h, and the maximum power density was about 6.3 w/m2 with an anion exchange membrane fuel cell (AEM_FC) and 4.4 w/m2 with a cation exchange membrane fuel cell (CEM_FC). Therefore, 90 mL of 0.1 M HCl was used as a catholyte to treat 20 L of 0.1 M NaHCO3 anolyte containing 1 ppm arsenate at an initial pH of 5 or 7. The arsenate level at pH 5 decreased to less than 5 ppb in 4 h, and the maximum power density was 5.9 W/m2 and 4.7 W/m2 with AEM_FC and CEM_FC, respectively. When using 0.01 M NaHCO3 as the anolyte at pH 5, arsenate was reduced to less than 5 ppb in 8 and 24 h for AEC_FC and CEM_FC, respectively. However, when using an anolyte at pH 7, arsenate could not be effectively removed in 24 h. Therefore, when using carbonate as an anolyte, the solution should be adjusted to a weakly acidic pH in order to remove arsenate.

Templated assembly of Co-Pt nanoparticles via thermal and laser-induced dewetting of bilayer metal films.

Templated dewetting of a Co/Pt metal bilayer film on a topographic substrate was used to assemble arrays of Co-Pt alloy nanoparticles, with highly uniform particle size, shape and notably composition compared to nanoparticles formed on an untemplated substrate. Solid-state and liquid-state dewetting processes, using furnace annealing and laser irradiation respectively, were compared. Liquid state dewetting produced more uniform, conformal nanoparticles but they had a polycrystalline disordered fcc structure and relatively low magnetic coercivity. In contrast, solid state dewetting enabled formation of magnetically hard, ordered L1(0) Co-Pt single-crystal particles with coercivity >12 kOe. Furnace annealing converted the nanoparticles formed by liquid state dewetting into the L1(0) phase.

Synthesis of symmetrical and unsymmetrical PAMAM dendrimers by fusion between azide- and alkyne-functionalized PAMAM dendrons.

A new convergent synthetic method for the synthesis of PAMAM dendrimers has been developed. The fusion between propargyl-functionalized PAMAM dendrons and azido-functionalized PAMAM dendrons via the Cu(I)-catalyzed Huisgen [2 + 3] dipolar cycloaddition reaction (click chemistry) of an alkyne and an azide leads to the formation of symmetric PAMAM dendrimers in high yields. Furthermore, the coupling reactions between the different generation dendrons afford the size-differentiated unsymmetrical PAMAM dendrimers.

Runx2 mediates FGF signaling from epithelium to mesenchyme during tooth morphogenesis.

Runx2 (Cbfa1) is a runt domain transcription factor that is essential for bone development and tooth morphogenesis. Teeth form as ectodermal appendages and their development is regulated by interactions between the epithelium and mesenchyme. We have shown previously that Runx2 is expressed in the dental mesenchyme and regulated by FGF signals from the epithelium, and that tooth development arrests at late bud stage in Runx2 knockout mice [Development 126 (1999) 2911]. In the present study, we have continued to clarify the role of Runx2 in tooth development and searched for downstream targets of Runx2 by extensive in situ hybridization analysis. The expression of Fgf3 was downregulated in the mesenchyme of Runx2 mutant teeth. FGF-soaked beads failed to induce Fgf3 expression in Runx2 mutant dental mesenchyme whereas in wild-type mesenchyme they induced Fgf3 in all explants indicating a requirement of Runx2 for transduction of FGF signals. Fgf3 was absent also in cultured Runx2-/- calvarial cells and it was induced by overexpression of Runx2. Furthermore, Runx2 was downregulated in Msx1 mutant tooth germs, indicating that it functions in the dental mesenchyme between Msx1 and Fgf3. Shh expression was absent from the epithelial enamel knot in lower molars of Runx2 mutant and reduced in upper molars. However, other enamel knot marker genes were expressed normally in mutant upper molars, while reduced or missing in lower molars. These differences between mutant upper and lower molars may be explained by the substitution of Runx2 function by Runx3, another member of the runt gene family that was upregulated in upper but not lower molars of Runx2 mutants. Shh expression in mutant enamel knots was not rescued by FGFs in vitro, indicating that in addition to Fgf3, Runx2 regulates other mesenchymal genes required for early tooth morphogenesis. Also, exogenous FGF and SHH did not rescue the morphogenesis of Runx2 mutant molars. We conclude that Runx2 mediates the functions of epithelial FGF signals regulating Fgf3 expression in the dental mesenchyme and that Fgf3 may be a direct target gene of Runx2.