Microfluidics‐Enabled Multimaterial Maskless Stereolithographic Bioprinting

A stereolithography‐based bioprinting platform for multimaterial fabrication of heterogeneous hydrogel constructs is presented. Dynamic patterning by a digital micromirror device, synchronized by a moving stage and a microfluidic device containing four on/off pneumatic valves, is used to create 3D constructs. The novel microfluidic device is capable of fast switching between different (cell‐loaded) hydrogel bioinks, to achieve layer‐by‐layer multimaterial bioprinting. Compared to conventional stereolithography‐based bioprinters, the system provides the unique advantage of multimaterial fabrication capability at high spatial resolution. To demonstrate the multimaterial capacity of this system, a variety of hydrogel constructs are generated, including those based on poly(ethylene glycol) diacrylate (PEGDA) and gelatin methacryloyl (GelMA). The biocompatibility of this system is validated by introducing cell‐laden GelMA into the microfluidic device and fabricating cellularized constructs. A pattern of a PEGDA frame and three different concentrations of GelMA, loaded with vascular endothelial growth factor, are further assessed for its neovascularization potential in a rat model. The proposed system provides a robust platform for bioprinting of high‐fidelity multimaterial microstructures on demand for applications in tissue engineering, regenerative medicine, and biosensing, which are otherwise not readily achievable at high speed with conventional stereolithographic biofabrication platforms.     

Metric-learning-based high-discriminative local features extraction for iris recognition

Pattern Analysis and Applications - Biometric-based authentication system is one of the main strategies to protect and control the access of users to important resources in any system and...     

The Optimization of Effective Factors on Mercaptan Extraction by Alkaline Solution

General LPG sweetening method used in Iran's South Pars Gas Complex is Sulfrex liquid-liquid extraction and caustic regeneration processes which uses caustic as alkaline solution to extract mercaptans from propane and butane cuts and also uses LCPS 30 as catalyst to regenerate of exhaust caustic. The authors focused on the extraction section process. Also effect of the main operating variables on mercaptans extraction, including extraction temperature, concentration, flow rate, and amount of caustic as alkaline solution were studied and at the end, according to laboratory results, operational process parameters were optimized and tuned.     

Effect of formulation ingredients on the physical characteristics of salmeterol xinafoate microparticles tailored by spray freeze drying

Series of microparticles containing salmeterol xinafoate (SX) as active pharmaceutical ingredient (API) and lactose, mannitol or trehalose as a bulking agents were prepared using spray freeze drying (SFD) technique and the effects of sugar type and presence of hydroxy propyl beta cyclodextrin (HPβCD) on the physical properties of powders were evaluated. Precipitation of salmeterol in the presence of lactose and mannitol resulted in the formation of irregular shapes of microparticles with broad size distributions. However application of trehalose resulted in the formation of porous particles with spherical morphology. Addition of cyclodextrin in the formulations was generally helpful for formation of porous and spherical particles with narrow size distribution with a mean size of 10–30 μm. Dissolution of SX from processed particles was substantially higher (～90% drug release in 30 min) than that of unprocessed drug and physical mixture of drug and cyclodextrin (～22% drug release in 30 min). This study showed that, processing of SX by SFD technique could be a constructive approach to the production of various forms of drug and drastic changes in the physical characteristics of microparticles could be achieved by changing the composition of bulking agent and cyclodextrin.     

Functionally Graded Materials Optimization Using Particle Swarm-Based Algorithms

This article presents an application of particle swarm-based algorithms for volume fraction optimization of functionally graded materials. A simple and efficient method for constraint handling is included too. To optimize the material composition, two numerical examples are done. In the first example, the peak residual stresses are minimized when the FGM is cooled from a reference temperature. In the second example, the factor of safety against yielding are maximized for a temperature-dependent FGM sphere subjected to thermal gradients. The algorithms PSO, PSOPC, PSACO and PSPCACO are used too and the optimum volume fraction are obtained. According comparison of the results, particle swarm-based algorithms can be used as a powerful tool for optimizing the FG materials.     

Carbon Nanotube–Ionic Liquid (CNT–IL) Nanocamposite Modified Sol-Gel Derived Carbon-Ceramic Electrode for Simultaneous Determination of Sunset Yellow and Tartrazine in Food Samples

Carbon-ceramic electrode modified with multi-walled carbon nanotubes–ionic liquid (MWCNTs–IL) nanocomposite was constructed. This electrode was used for electrochemical determination of food dyes Sunset Yellow (SY) and tartrazine (Tz). The modified electrode based on high surface area and high ionic conductivity of nanocomposite exhibited electrocatalytic effect for oxidation of SY and Tz; also, oxidation peak potentials of SY and Tz effectively separated on modified electrode, and their simultaneous determination was possible. Operational parameters, such as the amount of MWCNTs in suspension, IL volume, solution pH, and scan rate, which affect the analytical performance of determination, were optimized. The present electrode behaved linearly to Sunset Yellow and tartrazine in the concentration range of 4?×?10^?7 to 1.1?×?10^?4?M and 3?×?10^?6 to 0.7?×?10^?4?M with a detection limit of 10^?7?M (0.045 mg?L^?1) and 1.1?×?10^?6?M (0.59 mg?L^?1), respectively. The proposed method was successfully utilized for simultaneous determination of SY and Tz in different food samples, and the obtained results were in good agreement to those obtained by HPLC method.     

Studies of the entrapment of non-wetting fluid within nanoporous media using a synergistic combination of MRI and micro-computed X-ray tomography

Three-dimensional magnetic resonance imaging (MRI) and micro-computed X-ray tomography (micro-CXT) have been combined to study the entrapment of mercury within nanoporous silica materials following porosimetry. MR images have been used to construct structural models of particular porous media within which several simulations of mercury intrusion and retraction have been performed with variations in the mechanism for the ‘snap-off’ of the mercury menisci. The simulations gave rise to different predictions for the pattern of the macroscopic spatial distribution of entrapped mercury, depending on ‘snap-off’ mechanism, which were then compared with corresponding experimental data obtained from micro-CXT images of real pellets containing entrapped mercury. The information obtained from the micro-CXT images, and also from the porosimetry curves themselves, was then used to constrain a model for the microscopic mercury retraction mechanism. Additional predictions of the retraction model were then subsequently confirmed using scanning loop experiments. The simulations showed that the overall level of entrapment of mercury was determined by the close interaction between the pellet macroscopic structure (particularly pore size spatial correlation), and the microscopic mercury retraction mechanism. Hence, it was subsequently possible to explain fully why high mercury entrapment occurred within one particular type of sol-gel silica material, while only low entrapment occurred in another batch of superficially similar material.     

Developing a new method for spatial assessment of drought vulnerability (case study: Zayandeh‐Rood river basin in Iran)

The paper presents an approach to spatially representative depiction for assessing the vulnerability of central Iran's Zayandeh‐Rood river basin to drought using multiple indicators. Drought conditions prevailed in the study basin from 2002 to 2007, with an annual rainfall deficiency of 45 to 55%. Multi‐attribute decision making (MADM) methods develop a framework to evaluate the relative priorities of drought assessment based on a set of preferences, criteria and indicators. The proposed MADM process uses well‐known techniques for product weights analytic hierarchy process (AHP) and order preference (TOPSIS). These indicators include the Standard Precipitation Index (SPI), water demand, the Palmer Drought Severity Index (PDSI) and the Groundwater Balance and Surface Water Supply Index (SWSI). Indicators' spatial information was categorised in layers prepared in the spatial domain using a geographic information system (GIS). The alternatives were ranked and presented using TOPSIS. Results show that the proposed method was highly effective in representing assessments of drought vulnerability.     

Experimental measurement and modeling of saturated reservoir oil viscosity

A novel mathematical-based approach is proposed to develop reliable models for prediction of saturated crude oil viscosity in a wide range of PVT properties. A new soft computing approach, namely least square support vector machine modeling optimized with coupled simulated annealing optimization technique, is proposed. Six models have been developed to predict saturated oil viscosity, which are designed in such a way that could predict saturated oil viscosity with every available PVT parameter. The constructed models are evaluated by carrying out extensive experimental saturated crude oil viscosity data from Iranian oil reservoirs, which were measured using a “Rolling Ball viscometer.” To evaluate the performance and accuracy of these models, statistical and graphical error analyses were used simultaneously. The obtained results demonstrated that the proposed models are more robust, reliable and efficient than existing techniques for prediction of saturated crude oil viscosity.