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Fabrication of cardiac patch with decellularized porcine myocardial scaffold and bone marrow mononuclear cells

Tissue engineered cardiac grafts are a promising therapeutic mode for ventricular wall reconstruction. Recently, it has been found that acellular tissue scaffolds provide natural ultrastructural, mechanical, and compositional cues for recellularization and tissue remodeling. We thus assess the potential of decellularized porcine myocardium as a scaffold for thick cardiac patch tissue engineering. Myocardial sections with 2-mm thickness were decellularized using 0.1% sodium dodecyl sulfate and then reseeded with differentiated bone marrow mononuclear cells. We found that thorough decellularization could be achieved after 2.5 weeks of treatment. Reseeded cells were found to infiltrate and proliferate in the tissue constructs. Immunohistological staining studies showed that the reseeded cells maintained cardiomyocyte-like phenotype and possible endothelialization was found in locations close to vasculature channels, indicating angiogenesis potential. Both biaxial and uniaxial mechanical testing showed a stiffer mechanical response of the acellular myocardial scaffolds; however, tissue extensibility and tensile modulus were found to recover in the constructs along with the culture time, as expected from increased cellular content. The cardiac patch that we envision for clinical application will benefit from the natural architecture of myocardial extracellular matrix, which has the potential to promote stem cell differentiation, cardiac regeneration, and angiogenesis.

Myocardial Scaffold-based Cardiac Tissue Engineering: Application of Coordinated Mechanical and Electrical Stimulations

Recently, we developed an optimal decellularization protocol to generate 3D porcine myocardial scaffolds, which preserve the natural extracellular matrix structure, mechanical anisotropy, and vasculature templates and also show good cell recellularization and differentiation potential. In this study, a multistimulation bioreactor was built to provide coordinated mechanical and electrical stimulation for facilitating stem cell differentiation and cardiac construct development. The acellular myocardial scaffolds were seeded with mesenchymal stem cells (10(6) cells/mL) by needle injection and subjected to 5-azacytidine treatment (3 μmol/L, 24 h) and various bioreactor conditioning protocols. We found that after 2 days of culturing with mechanical (20% strain) and electrical stimulation (5 V, 1 Hz), high cell density and good cell viability were observed in the reseeded scaffold. Immunofluorescence staining demonstrated that the differentiated cells showed a cardiomyocyte-like phenotype by expressing sarcomeric α-actinin, myosin heavy chain, cardiac troponin T, connexin-43, and N-cadherin. Biaxial mechanical testing demonstrated that positive tissue remodeling took place after 2 days of bioreactor conditioning (20% strain + 5 V, 1 Hz); passive mechanical properties of the 2 day and 4 day tissue constructs were comparable to those of the tissue constructs produced by stirring reseeding followed by 2 weeks of static culturing, implying the effectiveness and efficiency of the coordinated simulations in promoting tissue remodeling. In short, the synergistic stimulations might be beneficial not only for the quality of cardiac construct development but also for patients by reducing the waiting time in future clinical scenarios.

Pilot scale fiber separation from distillers dried grains with solubles (DDGS) using sieving and air classification

Distillers dried grains with solubles (DDGS), the coproduct of fuel ethanol production from cereal grains like corn, is mainly used as cattle feed and is used at low inclusion levels in poultry and swine diets because of high fiber content. Elusieve process, the combination of sieving and air classification (elutriation), was developed in laboratory scale to separate fiber from DDGS to result in a low fiber product which would be more suitable for poultry and swine. In this pilot scale study, DDGS was sieved at a rate of 0.25 kg/s (1 ton/h) into four sieve fractions using a sifter and the three largest sieve fractions were air classified using aspirators to separate fiber on a continuous basis. Results were similar to laboratory scale. Nearly 12.4% by weight of DDGS was separated as Fiber product and resulted in two high protein products that had low fiber contents. Payback period for the Elusieve process in an existing dry grind plant processing corn at the rate of 2030 metric tonnes/day (80,000 bushels/day) would be 1.1 yr.

Synthesis of tungsten carbide nanoparticles in biochar matrix as a catalyst for dry reforming of methane to syngas

Tungsten carbide (WC) nanoparticles were synthesized by carbothermal reduction (CR) of tungsten-promoted biochar. The tungsten carbide nanoparticles were characterized for physicochemical properties by multiple morphological and structural methods (e.g. SEM, TEM, and XRD). Characterization results revealed that the transformation of tungsten oxide (WO3) to tungsten carbide nanoparticles involved the following sequence steps: WO3 → WO2 → W → W2C → WC. The lower the reaction temperature, the lower the CH4 and CO2 conversions, as well as the lower CO yield, since dry reforming is an endothermic reaction. CH4 conversion was observed to decrease with an increase in CH4/CO2 ratio, whereas CO2 conversion increased with an increase in CH4/CO2 ratio. The higher the GHSV, the lower the CH4 and CO2 conversions as well as the lower the CO yield. Stability testing of the tungsten carbide nanoparticles in the biochar matrix showed no catalyst deactivation during the 500 hours test duration.

Risk of low-level ionizing radiation from medical imaging procedures.

(Echocardiography 2011;28:593‐595)

A mathematical algorithm for quantification of CT image noise

Quantification of computed tomography (CT) noise helps in determination of radiation dosage requirements for adequate image quality. Clinical methods used include calculation of the standard deviation (SD) of a selected region of interest (ROI). In industry, wavelet decomposition has been used for image compression while removing high‐frequency noise. We evaluated a cohort of 74 consecutive patients referred for coronary artery calcium scoring and quantitated noise within a 16×16 ROI in the ascending aorta using the traditional SD method and also using a two‐dimensional dyadic wavelet decomposition method. Clinically, noise has been shown to be proportional to patient weight and also body mass index (BMI), which is a derived value from height and weight. Noise for both methods was plotted against patient parameters of height, weight, waist circumference and calculated BMI. A regression line was calculated and coefficient of determination (CoD) calculated for each. The CoD was better for height, weight, and waist circumference using the wavelet method as compared to the traditional SD method. The wavelet method of quantification of image noise may be an improved method as compared to the SD method. This method could help further refine an imaging systems determination of radiation dosage requirements to obtain a satisfactory quality image.

Feasibility Study of Utilizing Ultraportable Projectors for Endoscopic Video Display (With Videos)

Background. Modern endoscopy requires video display. Recent miniaturized, ultraportable projectors are affordable, durable, and offer quality image display. Objective. Explore feasibility of using ultraportable projectors in endoscopy. Methods. Prospective bench-top comparison; clinical feasibility study. Masked comparison study of images displayed via 2 Samsung ultraportable light-emitting diode projectors (pocket-sized SP-HO3; pico projector SP-P410M) and 1 Microvision Showwx-II Laser pico projector. Bench-top feasibility study: Prerecorded endoscopic video was streamed via computer. Clinical comparison study: Live high-definition endoscopy video was simultaneously displayed through each processor onto a standard liquid crystal display monitor and projected onto a portable, pull-down projection screen. Endoscopists, endoscopy nurses, and technicians rated video images; ratings were analyzed by linear mixed-effects regression models with random intercepts. Results. All projectors were easy to set up, adjust, focus, and operate, with no real-time lapse for any. Bench-top study outcomes: Samsung pico preferred to Laser pico, overall rating 1.5 units higher (95% confidence interval [CI] = 0.7-2.4), P < .001; Samsung pocket preferred to Laser pico, 3.3 units higher (95% CI = 2.4-4.1), P < .001; Samsung pocket preferred to Samsung pico, 1.7 units higher (95% CI = 0.9-2.5), P < .001. The clinical comparison study confirmed the Samsung pocket projector as best, with a higher overall rating of 2.3 units (95% CI = 1.6-3.0), P < .001, than Samsung pico. Conclusions. Low brightness currently limits pico projector use in clinical endoscopy. The pocket projector, with higher brightness levels (170 lumens), is clinically useful. Continued improvements to ultraportable projectors will supply a needed niche in endoscopy through portability, reduced cost, and equal or better image quality.

Recellularization Potential of Acellular Aortic Valve Scaffolds Treated With Collagenase and Acetic Acid

It is estimated that five million Americans suffer from moderate to severe aortic valve disease, making it the third most common type of cardiovascular disease. Aortic valve replacement, which is second leading reason for undergoing open heart surgery, is the prevailing treatment for patients with extensive aortic valve pathologies. Currently, substitute valves used to replace the disease valves are classified as either mechanical or biological, each of which carry significant disadvantages. Patients with mechanical valves are at a much higher risk for developing blood clots and therefore must remain on anticoagulants for the remainder of their lifetime; and biological valves, which are typically derived from porcine or cadeveric tissues, will deteriorate over time. The ideal replacement valve is one that presents no thrombogenicity or immunogenecity, provides normal hemodynamics, is free of blood damaging elements, offers a practical mode for implantation, is able to grow and remodel, and does not deteriorate over time.© 2009 ASME

Effects of Feedstock Properties on the Performance of A Downdraft Gasifier

Physicochemical properties of biomass feedstocks, such as composition, shape, size, moisture content, etc., have profound effects on the gasification process. The properties affect feedstock selection, sizing, transportation, and storage; gasification and syngas recovery, and residue or co-product processing. The extent of the effects of feedstock properties depend on gasfier type, operating conditions, and syngas quality product requirements. Fixed-bed downdraft gasifiers are widely used in small-scale biomass gasification facilities because of their simple and robust construction, easy and reliable operation, suitability with various feedstocks, high conversion rate, and production of relatively clean syngas containing low tar and particulate concentrations. A series of gasification tests using different biomass feedstocks, including hardwood chips, softwood chips, softwood sawdust, corn cubes, crude glycerol (a byproduct of biodiesel production), and switchgrass, were conducted under similar operating conditions using a pilot scale fixed-bed downdraft gasifier. The results show that downdraft gasifier is suitable for gasifying diverse feedstocks to produce good quality syngas with good low heating value and low tar and particle concentrations. There are no significant differences in gas composition, low-heating value, tar and particle concentrations among the different feedstocks used in the experiments. The syngas produced by the gasification process can be directly be used as fuel in internal combustion engines (ICE), however the physicochemical properties of feedstock such as shape, size, porosity, and the chemical contents, was found to affect the performance of the fixed-bed downdraft gasifier. Feedstocks with small sizes, low porosity, or containing highly compounds that can caramelize in high temperature could cause problems with bridging, lumping, collapsing, or clogging inside the reaction chamber and could cause the gasifier to fail. Hardwood chips mixed with 20% of liquid crude glycerol can be gasified well in the downdraft gasifier and produced syngas with significant higher CH4 content, good low-heating value and lower tar concentration than those of regular hardwood chips.

Modeling Evaluation of Micro-scale Electricity Generation Cost form Biomass Synthetic Gas

A promising renewable energy pathway is electricity generated with synthetic gas (syngas) from biomass. The feasibility of using gasification for generating electrical power is very much dependent on the cost of the power plant and the cost of its operation. A mathematical costing model was developed to analyze the Unit Cost (unit-cost) of electricity generation from micro-scale power facilities that used biomass gasification as its energy input. The costs considered in the model were capital cost and operating costs. The results from the model indicated that operating cost was a major part of the total annual cost of electricity generation, and that labor was the largest part of the total annual cost of operation, and it was during the time when the power facilities operated at lower generation capacity levels. One effective way of reducing the unit-cost was to operate the facility at high capacity level. The study found that when the capacity level increased the total of annual cost was also increased, but the electricity unit cost decreased markedly. For a given level of generating capacity the electricity unit cost of the system operating at a three shifts working model was significantly lower than that of one shift working model.