Nano-mechanical transduction of polymer micro-cantilevers to detect bio-molecular interactions

Using variothermal polymer micro-injection molding, disposable arrays of eight polymer micro-cantilevers each 500 μm long, 100 μm wide and 25 μm thick were fabricated. The present study took advantage of an easy flow grade polypropylene. After gold coating for optical read-out and asymmetrical sensitization, the arrays were introduced into the Cantisens(®) Research system to perform mechanical and functional testing. We demonstrate that polypropylene cantilevers can be used as biosensors for medical purposes in the same manner as the established silicon ones to detect single-stranded DNA sequences and metal ions in real-time. A differential signal of 7 nm was detected for the hybridization of 1 μM complementary DNA sequences. For 100 nM copper ions the differential signal was found to be (36 ± 5) nm. Nano-mechanical sensing of medically relevant, nanometer-size species is essential for fast and efficient diagnosis.

Heuristic decomposition and LP-based scheduling in make-and-pack production

In this paper, we are concerned about the short-term scheduling of industrial make-and-pack production processes. The planning problem consists in minimizing the production makespan while meeting given end-product demands. Sequence-dependent changeover times, multi-purpose storage units with finite capacities, quarantine times, batch splitting, partial equipment connectivity, material transfer times, and a large number of operations contribute to the complexity of the problem. Known MILP formulations cover all technological constraints of such production processes, but only small problem instances can be solved in reasonable CPU times. In this paper, we develop a heuristic in order to tackle large instances. Under this heuristic, groups of batches are scheduled iteratively using a novel MILP formulation; the assignment of the batches to the groups and the scheduling sequence of the groups are determined using a priority rule. We demonstrate the applicability by means of a real-world production process.

Plasma-functionalized electrospun matrix for biograft development and cardiac function stabilization.

Cardiac tissue engineering approaches can deliver large numbers of cells to the damaged myocardium and have thus increasingly been considered as a possible curative treatment to counteract the high prevalence of progressive heart failure after myocardial infarction (MI). Optimal scaffold architecture and mechanical and chemical properties, as well as immune- and bio-compatibility, need to be addressed. We demonstrated that radio-frequency plasma surface functionalized electrospun poly(ɛ-caprolactone) (PCL) fibres provide a suitable matrix for bone-marrow-derived mesenchymal stem cell (MSC) cardiac implantation. Using a rat model of chronic MI, we showed that MSC-seeded plasma-coated PCL grafts stabilized cardiac function and attenuated dilatation. Significant relative decreases of 13% of the ejection fraction (EF) and 15% of the fractional shortening (FS) were observed in sham treated animals; respective decreases of 20% and 25% were measured 4 weeks after acellular patch implantation, whereas a steadied function was observed 4 weeks after MSC-patch implantation (relative decreases of 6% for both EF and FS).

Mechanical restoration and failure analyses of a hydrogel and scaffold composite strategy for annulus fibrosus repair

Unrepaired defects in the annulus fibrosus of intervertebral disks are associated with degeneration and persistent back pain. A clinical need exists for a disk repair strategy that can seal annular defects, be easily delivered during surgical procedures, and restore biomechanics with low risk of herniation. Multiple annulus repair strategies were developed using poly(trimethylene carbonate) scaffolds optimized for cell delivery, polyurethane membranes designed to prevent herniation, and fibrin-genipin adhesive tuned to annulus fibrosus shear properties. This three-part study evaluated repair strategies for biomechanical restoration, herniation risk and failure mode in torsion, bending and compression at physiological and hyper-physiological loads using a bovine injury model. Fibrin-genipin hydrogel restored some torsional stiffness, bending ROM and disk height loss, with negligible herniation risk and failure was observed histologically at the fibrin-genipin mid-substance following rigorous loading. Scaffold-based repairs partially restored biomechanics, but had high herniation risk even when stabilized with sutured membranes and failure was observed histologically at the interface between scaffold and fibrin-genipin adhesive. Fibrin-genipin was the simplest annulus fibrosus repair solution evaluated that involved an easily deliverable adhesive that filled irregularly-shaped annular defects and partially restored disk biomechanics with low herniation risk, suggesting further evaluation for disk repair may be warranted. Statement of significance Lower back pain is the leading cause of global disability and commonly caused by defects and failure of intervertebral disk tissues resulting in herniation and compression of adjacent nerves. Annulus fibrosus repair materials and techniques have not been successful due to the challenging mechanical and chemical microenvironment and the needs to restore biomechanical behaviors and promote healing with negligible herniation risk while being delivered during surgical procedures. This work addressed this challenging biomaterial and clinical problem using novel materials including an adhesive hydrogel, a scaffold capable of cell delivery, and a membrane to prevent herniation. Composite repair strategies were evaluated and optimized in quantitative three-part study that rigorously evaluated disk repair and provided a framework for evaluating alternate repair techniques.

Index Tracking Using Data-Mining Techniques and Mixed-Binary Linear Programming

Index tracking has become one of the most common strategies in asset management. The index-tracking problem consists of constructing a portfolio that replicates the future performance of an index by including only a subset of the index constituents in the portfolio. Finding the most representative subset is challenging when the number of stocks in the index is large. We introduce a new three-stage approach that at first identifies promising subsets by employing data-mining techniques, then determines the stock weights in the subsets using mixed-binary linear programming, and finally evaluates the subsets based on cross validation. The best subset is returned as the tracking portfolio. Our approach outperforms state-of-the-art methods in terms of out-of-sample performance and running times.

Delayed Thrombus Resolution and Fibroproliferative Vascular Wound Healing From Deficiency of Type III Collagen: a Paradoxical Mechanism for Tissue Fragility

Vascular Ehlers-Danlos syndrome is a heritable disease of connective tissue caused by mutations in COL3A1, conferring a tissue deficiency of type III collagen. Cutaneous wounds heal poorly in these patients, and they are susceptible to spontaneous and catastrophic rupture of expansible hollow organs like the gut, uterus, and medium-sized to large arteries, which leads to premature death. Although the predisposition for organ rupture is often attributed to inherent tissue fragility, investigation of arteries from a haploinsufficient Col3a1 mouse model (Col3a1+/-) demonstrates that mutant arteries withstand even supraphysiologic pressures comparably to wild-type vessels. We hypothesize that injury that elicits occlusive thrombi instead unmasks defective thrombus resolution resulting from impaired production of type III collagen, which causes deranged remodeling of matrix, persistent inflammation, and dysregulated behavior by resident myofibroblasts, culminating in the development of penetrating neovascular channels that disrupt the mechanical integrity of the arterial wall. Vascular injury and thrombus formation following ligation of the carotid artery reveals an abnormal persistence and elevated burden of occlusive thrombi at 21 post-operative days in vessels from Col3a1+/- mice, as opposed to near complete resolution and formation of a patent and mature neointima in wild-type mice. At only 14 days, both groups harbor comparable burdens of resolving thrombi, but wild-type mice increase production of type III collagen in actively resolving tissues, while mutant mice do not. Rather, thrombi in mutant mice contain higher burdens of macrophages and proliferative myofibroblasts, which persist through 21 days while wild-type thrombi, inflammatory cells, and proliferation all regress. At the same time that increased macrophage burdens were observed at 14 and 21 days post ligation, the medial layer of mutant arterial walls concurrently harbored a significantly higher incidence of penetrating neovessels compared with those in wild-type mice. To assess whether limited type III collagen production alters myofibroblast behavior, fibroblasts from vEDS patients with COL3A1 missense mutations were seeded into three-dimensional fibrin gel constructs and stimulated with transforming growth factor-β1 to initiate myofibroblast differentiation. Although early signaling events occur similarly in all cell lines, late extracellular matrix- and mechanically-regulated events like transcriptional upregulation of type I and type III collagen secretion are delayed in mutant cultures, while transcription of genes encoding intracellular contractile machinery is increased. Sophisticated imaging of collagen synthesized de novo by resident myofibroblasts visualizes complex matrix reorganization by control cells but only meager remodeling by COL3A1 mutant cells, concordant with their compensatory contraction to maintain tension in the matrix. Finally, administration of immunosuppressive rapamycin to mice following carotid ligation sufficiently halts the initial inflammatory phase of thrombus resolution and fully prevents both myofibroblast migration into the thrombus and the differential development of neovessels between mutant and wild-type mice, suggesting that pathological defects in mutant arteries develop secondarily to myofibroblast dysfunction and chronic inflammatory stimulation, rather than as a manifestation of tissue fragility. Together these data establish evidence that pathological defects in the vessel wall architecture develop in mutant arteries as sequelae to abnormal healing and remodeling responses activated by arterial injury. Thus, these data support the hypothesis that events threatening the integrity of type III collagen-deficient vessels develop not as a result of inherent tissue weakness and fragility at baseline but instead as an episodic byproduct of abnormally persistent granulation tissue and fibroproliferative intravascular remodeling.

Proceedings of the Nineteenth Annual Biochemical Engineering Symposium

The nineteenth symposium was held at the University of Missouri–Columbia on April 22, 1989. A total of eighteen papers were scheduled for presentation, of which nine were in poster session. Finally, fifteen papers were presented and sixteen were submitted for this proceedings. It was attended by 53 participants from five institutions. A sixth group (from Colorado State University) was kept from attending the symposium due to mechanical problems on the road and we missed them. Since they worked hard at their presentations, I requested CSU-group to submit their papers for the proceedings and I am happy that they did. ContentsMathematical modelling of a flour milling system. K. Takahashi, Y. Chen, J. Hosokoschi, and L. T. Fan. Kansas State University A novel solution to the problem of plasmid segregation in continuous bacterial fermentations. K.L. Henry, R. H. Davis, and A. L. Taylor. University of Colorado Modelling of embryonic growth in avian and reptile Eggs. C.L. Krause, R. C. Seagrave, and R. A. Ackerman. Iowa State University Mathematical modeling of in situ biodegradation processes. J.C. Wu, L. T. Fan, and L. E. Erickson. Kansas State University Effect of molecular changes on starch viscosity. C.H. Rosane and V. G. Murphy. Colorado State University Analysis of two stage recombinant bacterial fermentations using a structured kinetic model. F. Miao and D. S. Kampala. University of Colorado Lactic acid fermentation from enzyme-thinned starch by Lactobacillus amylovorus. P.S. Cheng, E. L. Iannotti, R. K. Bajpai, R. Mueller, and s. Yaeger. University of Missouri–Columbia Solubilization of preoxidized Texas lignite by cell-free broths of Penicillium strains. R. Moolick, M. N. Karim, J. C. Linden, and B. L. Burback. Colorado State University Separation of proteins from polyelectrolytes by ultrafiltration. A.G. Bazzano and C. E. Glatz. Iowa State University Growth estimation and modelling of Rhizopus oligosporus in solid state fermentations. D.-H. Ryoo, V. G. Murphy, M. N. Karim, and R. P. Tengerdy. Colorado State University Simulation of ethanol fermentations from sugars in cheese whey. C.J. Wang and R. K. Bajpai. University of Missouri–Columbia Studies on protoplast fusion of B. licheniformis. B. Shi, Kansas State University Cell separations of non-dividing and dividing yeasts using an inclined settler. C.-Y. Lee, R. H. Davis, and R. A. Sclafani. University of Colorado Effect of·serum upon local hydrodynamics within an airlift column. G.T. Jones, L. E. Erickson, and L. A. Glasgow. Kansas State University Optimization of heterologous protein secretion in continuous culture. A. Chatterjee, W. F. Remirez, and R. H. Davis. University of Colorado An improved model for lactic acid fermentation. P. Yeh, R. K. Bajpai, and E. L. Iannotti. University of Missouri–Columbia

Ag Engineering and Agronomy Farm and Central Iowa Research Farms Summary

Includes Ag Engineering and Agronomy Farm Farm and Weather Summary, Central Iowa Farms Farm and Weather Summary and Project Lists