Bioactive-Tissue-Derived Nanocomposite Hydrogel for Permanent Arterial Embolization and Enhanced Vascular Healing

Transcatheter embolization is a minimally invasive procedure that uses embolic agents to intentionally block diseased or injured blood vessels for therapeutic purposes. Embolic agents in clinical practice are limited by recanalization, risk of non-target embolization, failure in coagulopathic patients, high cost, and toxicity. Here, a decellularized cardiac extracellular matrix (ECM)-based nanocomposite hydrogel is developed to provide superior mechanical stability, catheter injectability, retrievability, antibacterial properties, and biological activity to prevent recanalization. The embolic efficacy of the shear-thinning ECM-based hydrogel is shown in a porcine survival model of embolization in the iliac artery and the renal artery. The ECM-based hydrogel promotes arterial vessel wall remodeling and a fibroinflammatory response while undergoing significant biodegradation such that only 25% of the embolic material remains at 14 days. With its unprecedented proregenerative, antibacterial properties coupled with favorable mechanical properties, and its superior performance in anticoagulated blood, the ECM-based hydrogel has the potential to be a next-generation biofunctional embolic agent that can successfully treat a wide range of vascular diseases.     

Deformation of glassy polycarbonate and polystyrene: the influence of chemical structure and local environment

Understanding the mechanism of deformation is very important in various applications. Although the stress-strain behavior of crystals and glasses are similar, the mechanism of deformation is very different. We used molecular dynamics to study polycarbonate and polystyrene under constant external loads. The results indicate that high atomic/segmental mobility and low local density enable the formation (nucleation) of highly deformed regions that grow to form plastic defects, and the effect of chemical structure was found to dominate the deformation mechanism     

Effects of aging on latex film formation from polystrene particles: A photon transmission study

Aging due to the storage time on latex film formation was studied using the photon transmission method. The UV visible technique was used to monitor the evolution of transparency during film formation from two different polystyrene (PS) particles produced by using two different steric stabilizers, i.e., polyvinyl alcohol and polyvinyl pyrrolidone. The latex films were prepared from PS particles at room temperature before and after aging and annealed at elevated temperatures in various time intervals above glass transition (T_g). The increase in the transmitted photon intensity I_tr was attributed to the increase in the number of disappeared particle–particle interfaces. Relative decrease in transparency and delay in film formation were observed in the aged latex films compared to the nonaged ones. The Prager–Tirrell model was employed to interpret the increase in crossing density at the junction surface. The back and forth activation energies (ΔE) were measured and found to be dependent on aging for a diffusing polymer chain across the junction surface. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 79: 2014–2021, 2001     

Molecular weight dependent changes with time during latex film formation: a photon transmission study

A photon transmission method was used to probe the change with time of transparency during film formation from latex particles. Two different latex films were prepared from high (HM) and low (LM) molecular weight poly(methyl methacrylate) (PMMA) particles, which were annealed at 10min time intervals at various temperatures above the glass transition T_g. The increase in the transmitted photon intensity I_tr is attributed to the increase in ‘crossing density’ at the junction surface. The back and forth activation energies (ΔE) were measured for HM and LM films and found to be around 29kcalmol^-1 and 53kcalmol^-1, respectively, for a reptating polymer chain across the junction surface. Monte Carlo simulations were performed for photon transmission through a rectangular lattice. The number of transmitted photons N_tr was calculated as a function of the mean free path of the photons. It was observed that N_tr increased similarly to I_tr as the square of the mean free path of the photons increased. © 1998 Society of Chemical Industry     

Fluorescence and UV techniques for studying neck growth and equilibration processes during latex film formation

Steady state fluorescence (SSF) and UV–visible techniques have been used to study neck growth and equilibration processes during the coalescence of hard latex particles. Latex films were prepared separately by annealing pyrene (P_y) labelled and unlabelled poly(methyl methacrylate) (PMMA) particles above their glass transition temperature. During the annealing processes, the optical clarity of the films increased considerably. Direct fluorescence emission of excited pyrene from labelled latex films was monitored as a function of annealing temperature to detect this change. Void closure temperature (T_c) and time (t_c) were determined at the point where the fluorescence emission intensity became maximal. Below this point, the increase in fluorescence intensity (I_op) against temperature was used to determine the activation energy for viscous flow (ΔH≈47kcalmol⁻¹). The decrease in I_op above the void closure temperature was used to determine the backbone activation energy (ΔE≈44kcalmol⁻¹) for the interdiffusing chains. Unlabelled PMMA particles were used to prepare films for UV–vis measurements. The transmitted photon intensity (I_tr) from these films increased as the annealing temperature was increased. This behaviour was also used to determine the backbone activation energy (ΔE≈35kcalmol⁻¹) for the interdiffusing chains. © Society of Chemical Industry.     

Determination of Chloroanisoles and Chlorophenols in Cork and Wine by using HS‐SPME and GC‐ECD Detection

Cork taint is an off‐flavor problem in wine, the main reason being the presence of 2,4,6‐trichloroanisole (TCA) in the cork stopper. In addition to the TCA, the presence of other chloroanisole and chlorophenol family compounds (the perception limits of which are very low) can also result in, or contribute to, cork taint problem. In this study, the levels of 2,4‐dichloroanisole (DCA), 2,4,6‐trichloroanisole (TCA), 2,3,4,6‐tetrachloroanisole (TeCA), pentachloroanisole (PCA), 2,4,6‐trichlorophenol (TCP), 2,3,4,6‐tetrachlorophenol (TeCP) and penthaclorophenol (PCP) were assayed in cork stoppers (natural, agglomerated and colmate) and in red wine samples from different wineries in Turkey using HS‐SPME and GC‐ECD detection. The performance parameters for all chloroanisole and chlorophenol compounds were as follows: recovery 92.48–102.53%, R 0.992‐0.996. The LOQ values were DCA (8.4 ng/L), TCA (0.8 ng/L), TeCa (0.6 ng/L), PCP (0.8 ng/L), TCP (0.8 ng/L), TeCP (1.2 ng/L), and PCP (1.1 ng/L) respectively. In cork stoppers, the amounts of 2,4,6 TCA ranged between 5.4–130.6 ng/g. The 2,3,4,6 TeCA ranged between 1.12‐8.2 ng/g and the PCA ranged between nd (not detected)‐11.01 ng/g. In the wine samples, 2,4,6 TCA ranged between 1.42–70.2 ng/L. The 2,3,4,6 TeCA ranged between nd‐15.1 ng/L and the PCA ranged from nd‐5.16 ng/L. The results indicated that there was a significant correlation between the TCA in wines and the TCA in cork stoppers.     

Numerical and modeling issues in application of CFD to flow in a simplified plenum relevant to a prismatic VHTR

Computational Fluid Dynamics (CFD) calculations have been performed for turbulent flow inside a plenum model that resembles a section of the lower plenum of a typical helium-cooled prismatic Very High Temperature Reactor (VHTR). Different Reynolds Averaged Navier-Stokes (RANS) based turbulence models are employed to investigate the capability in capturing unsteady large scale coherent structures due to vortex shedding at two different Reynolds numbers. A grid convergence study is conducted with those models which were able to capture unsteady vortex shedding. The non-linear interaction of mesh quality, turbulence model and numerical scheme lead to flow regime changes with significantly different unsteady behaviors. This makes it difficult to assess numerical and modeling uncertainty using the procedures available in the literature. Some remedies to overcome this difficulty are recommended. The numerical uncertainty in the local values of velocity components at selected locations inside the plenum, as well as the uncertainty associated with derived quantities such as wall shear stress at critical locations are calculated and reported. Since there are no experiments corresponding to the present cases simulated, the current analysis can be considered as a blind application of the proposed uncertainty estimation procedures.     

Radar‐based structural health monitoring of wind turbine blades: The case of damage localization

This short communication reports on a radar approach for structural health monitoring of wind turbine blades. Therefore, a bistatic frequency‐modulated continuous wave (FMCW) radar in the frequency range from 33.4 to 36.0 GHz has been developed and tested experimentally using a laboratory wind turbine demonstrator. A differential damage localization framework is presented here that exploits signal differences between measurements from the intact and the damaged structure for 3D imaging of the defect. We have achieved the localization of a 30‐mm cut in a glass fiber composite structure as well as the localization of a water pack at the backside of the specimen with a localization error of several centimeters.     

The tricriteria flowshop scheduling problem

Multicriteria flowshop scheduling problems have been one of the most attractive subjects in recent years. In the multicriteria flowshop scheduling literature, a very limited number of studies have been performed on problems which include a tardiness criterion. In this paper a multicriteria (tricriteria) two-machine flowshop scheduling problem with a tardiness criterion is tackled. The objective is to minimise a weighted sum of total completion time, total tardiness and makespan. An integer programming model is proposed for the problem which belongs to NP-hard class. The modified NEH (Nawaz, Enscore and Ham) algorithm, a tabu search-based heuristic method, random search and the EDD rule (the earliest due date rule) are used to solve problems with up to 2,500 jobs. A computational analysis is conducted to evaluate the performance of the heuristics. The analysis shows that the heuristics are quite efficient, and the performance of the tabu search based heuristic is the best of all in terms of solution quality.     

Systematic mesh development for 3D CFD simulation of fixed beds: Single sphere study

To develop and validate meshes for computational fluid dynamics (CFD) simulations of transport in fixed beds, a single particle is often used as a test case. We present results for drag coefficient (C_D) and heat transfer Nusselt number (Nu) for flow past a sphere, focusing on high flow rates typical of industrial steam reformers (400 < Re < 20,000). Over this range, good predictions of C_D were obtained using large eddy simulation (LES) to capture vortex shedding and wake dynamics, with a mesh refined downstream from the sphere. The small time-steps and high cell count required make this too expensive for fixed beds. Nu can be accurately calculated using a Reynolds-averaged Navier-Stokes (RANS) method with shear-stress transport (SST) k-ω closure provided the mesh at the particle surface is fine enough and covers most of the boundary layer. Single sphere simulations of heat transfer are more useful for fixed bed mesh development than drag coefficient calculations.