Elastomeric Fibrous Hybrid Scaffold Supports In Vitro and In Vivo Tissue Formation

Biomimetic materials with biomechanical properties resembling those of native tissues while providing an environment for cell growth and tissue formation, are vital for tissue engineering (TE). Mechanical anisotropy is an important property of native cardiovascular tissues and directly influences tissue function. This study reports fabrication of anisotropic cell‐seeded constructs while retaining control over the construct's architecture and distribution of cells. Newly synthesized poly‐4‐hydroxybutyrate (P4HB) is fabricated with a dry spinning technique to create anelastomeric fibrous scaffold that allows control of fiber diameter, porosity, and rate ofdegradation. To allow cell and tissue ingrowth, hybrid scaffolds with mesenchymalstem cells (MSCs) encapsulated in a photocrosslinkable hydrogel were developed. Culturing the cellularized scaffolds in a cyclic stretch/flexure bioreactor resulted in tissue formation and confirmed the scaffold's performance under mechanical stimulation. In vivo experiments showed that the hybrid scaffold is capable of withstanding physiological pressures when implanted as a patch in the pulmonary artery. Aligned tissue formation occurred on the scaffold luminal surface without macroscopic thrombus formation. This combination of a novel, anisotropic fibrous scaffold and a tunable native‐like hydrogel for cellular encapsulation promoted formation of 3D tissue and provides a biologically functional composite scaffold for soft‐tissue engineering applications.     

Hydrogen desorption properties of MgH2-TiCr1.2Fe0.6 nanocomposite prepared by high-energy mechanical alloying

In the present work, high-energy mechanical alloying (MA) was employed to synthesize a nanostructured magnesium-based composite for hydrogen storage. The preparation of the composite material with composition of MgH₂-5 at% (TiCr_1.2Fe_0.6) was performed by co-milling of commercial available MgH₂ powder with the body-centered cubic (bcc) alloy either in the form of Ti-Cr-Fe powder mixture with the proper mass fraction (sample A) or prealloyed TiCr_1.2Fe_0.6 powder (sample B). The prealloyed powder with an average crystallite size of 14 nm and particle size of 384 nm was prepared by the mechanical alloying process. It is shown that the addition of the Ti-based bcc alloy to magnesium hydride yields a finer particle size and grain structure after mechanical alloying. As a result, the desorption temperature of mechanically activated MgH₂ for 4 h decreased from 327 °C to 262 °C for sample A and 241 °C for sample B. A high dehydrogenation capacity (∼5 wt%) at 300 °C is also obtained. The effect of the Ti-based alloy on improvement of the dehydrogenation is discussed.     

A new, simple method for the production of meat-curing pigment under optimised conditions using response surface methodology

The production of cured meat pigment using nitrite and ascorbate in acidic conditions was evaluated. HCl, ascorbate and nitrite concentrations were optimised at three levels using the response surface method (RSM). The effects of process variables on the nitrosoheme yield, the wavelength of maximum absorbance (λ(max)), and L*, a* and b* values were evaluated. The response surface equations indicate that variables exerted a significant effect on all dependent factors. The optimum combinations for the reaction were HCl=-0.8, ascorbate=0.46 and nitrite=1.00 as coded values for conversion of 1mM hemin to nitrosoheme, by which a pigment yield of 100%, which was similar to the predicted value of 99.5%, was obtained. Likewise, the other parameters were not significantly different from predicted values as the λ(max), L*, a* and b* values were 558nm, 47.03, 45.17 and 17.20, respectively. The structure of the pigment was identified using FTIR and ESI/MS.     

Evaluation of antioxidant activities of Iranian sumac (R. coriaria L.) fruit and spice extracts with different solvents

The antioxidant capacity and phenolic content of three sumac (Rhus coriaria L.) samples, including brown sumac fruit, brown sumac powder and red sumac powder were investigated in the present study. Methanol, ethanol, distilled water, and a mixture of methanol and ethanol (1:1) were used as solvent systems. Antioxidant activities of extracts were screened using 1,1-diphenyl-2-picrylhydrazyl DPPH radical scavenging method. Phenolic content was determined through Folin–Ciocaltaeu procedure. The efficiency of the solvents used to extract phenols from the samples varied considerably. The phenolic content of brown sumac powder ranged from 2.906 to 2.997 gallic acid equivalents/100 g (GAE/100 g), while that of the brown sumac fruit was 2.438–2.529 GAE/100 g, and that of the red sumac powder was 2.172–2.263 GAE/100 g. Findings indicated that water extracts of sumac have effective antioxidant and radical scavenging activities as compared to other extracts.     

Optimistic Selection of Cluster Heads Based on Facility Location Problem in Cluster-Based Routing Protocols

Cluster-based routing protocols are one of the most favorable approaches for energy management in wireless sensor networks. The selection of the best cluster heads (CHs), as well as the formation of optimal clusters, is an NP-hard problem. The present study proposes an optimal solution for CHs selection to generate a network topology with optimized network performance. The problem is formulated as facility location problem and a linear programming model is used to solve the optimization problem. Results of analysis o the network simulator (NS2) indicate that applying this method in cluster-based routing protocols prolongs 16 % of the network lifetime, increases 15.5 % of data transmission and improves 5.5 % of throughput, as compared to the results of current heuristic methods such as LEACH, DEEC and EDFCM protocols.     

Physicochemical Properties of Foam‐Templated Oleogel Based on Gelatin and Xanthan Gum

In this paper, gelatin and xanthan are applied to produce a foam‐templated oleogel. For this reason, the oleogel is prepared at different concentrations of biopolymers and the properties of solution, cryogel, and related oleogel are determined. The results show that xanthan addition increases viscosity and foam stability of solution. Also, an increment in biopolymer concentration increases cryogel network density (ND) and firmness but has no significant effect on moisture sorption. The oil binding capacity of all oleogels is >92%. In terms of high foam stability (96.87 ± 4.42), low ND (0.016 ± 0.00), and consequently suitable oil sorption (46.10 ± 4.40), the oleogel containing 3% gelatin and 0.2% xanthan is selected as the best sample. Complementary tests exhibit that the oleogel, with thixotropic behavior and 60% structural recovery, can bind the oil at temperature <100 °C. The oleogel network can protect the edible oil from oxidative reaction during 2 month storage. Nonetheless, more studies are needed to attest the application of this oleogel type in food products. Practical Application: Biopolymers of gelatin and xanthan are GRAS and available so that they are applied in many food products. This research shows that the cryogel of these biopolymers, as a hydrophilic oleogelator, can be utilized to structure oil and produce oleogel in an indirect method. This procedure that forms strong gel and keeps oil even at high temperatures can be of interest to scientists who are searching for solid fat substitutes in food products such as cakes, biscuits, and muffins.     

Measurement matrix design for CS-MIMO radar using multi-objective optimization

In this paper, we design a measurement matrix for a compressive sensing-multiple-input multiple-output radar in the presence of clutter and interference. To optimize the measurement matrix, three main criteria are considered simultaneously to improve detection and sparse recovery performance while suppressing clutter and interference. To this end, we consider three well-known criteria including Bhattacharyya distance, mutual coherency of sensing matrix, and signal-to-clutter-plus-interference ratio. Due to the use of simultaneous multi-objective functions, a multi-objective optimization (MOO) framework is exploited. Some numerical examples are provided to illustrate the achieved improvement of our proposed method in target detection and sparse recovery performance. Simulation results show that the proposed MOO technique for measurement matrix design can achieve superior performance in target detection compared with Gaussian random measurement matrix technique.     

Discrete-time fractional-order PID controller: Definition,tuning, digital realization and some applications

In some of the complicated control problems we have to use the controllers that apply nonlocal operators to the error signal to generate the control. Currently, the most famous controller with nonlocal operators is the fractional-order PID (FOPID). Commonly, after tuning the parameters of FOPID controller, its transfer function is discretized (for realization purposes) using the so-called generating function. This discretization is the origin of some errors and unexpected results in feedback systems. It may even happen that the controller obtained by discretizing a FOPID controller works worse than a directly-tuned discrete-time classical PID controller. Moreover, FOPID controllers cannot directly be applied to the processes modeled by, e.g., the ARMA or ARMAX model. The aim of this paper is to propose a discrete-time version of the FOPID controller and discuss on its properties and applications. Similar to the FOPID controller, the proposed structure applies nonlocal operators (with adjustable memory length) to the error signal. Two methods for tuning the parameters of the proposed controller are developed and it is shown that the proposed controller has the capacity of solving complicated control problems.