Nanoscale Optoregulation of Neural Stem Cell Differentiation by Intracellular Alteration of Redox Balance

Regulation of stem cell (SC) fate, a decision between self‐renewal and differentiation, is of immense importance in regenerative medicine and has been proven to be a powerful stimulus regulating many cell functions influencing the SC fate. This study uses triphenylphosphonium‐functionalized gold nanoparticles (TPP‐AuNPs) to explore the interplay of intracellular electromagnetic (EM) exposure and the SC fate. Localized EM waves are generated inside neural stem cells (NSCs) to stimulate TPP‐AuNPs (AuNPs), targeting the mitochondria through inducing reactive oxygen species and differentiating these cells into neurons. Following laser irradiation of TPP‐AuNPs‐transfected NSCs, their differentiation to neurons is monitored by tracing the relevant markers both at the genetic and protein levels. The electrophysiology technique is further used to examine the functionality of neurons. The results confirm that TPP‐AuNPs subjected to electromotive forces have the potential to regulate cellular fate, although further investigations are still required to shed light on the mechanisms underlying the interaction of EM‐stimulated TPP‐AuNPs on cellular fate to design highly adjustable cell differentiation and reprogramming methods.     

Differential quadrature method for nonlocal nonlinear vibration analysis of a boron nitride nanotube using sinusoidal shear deformation theory

This article presents a nonlocal sinusoidal shear deformation beam theory (SDBT) for the nonlinear vibration of single-walled boron nitride nanotubes (SWBNNTs). The surrounding elastic medium is simulated based on nonlinear Pasternak foundation. Based on the nonlocal differential constitutive relations of Eringen, the equations of motion of the SWBNNTs are derived using Hamilton's principle. Differential quadrature method (DQM) for the nonlinear frequency is presented, and the obtained results are compared with those predicted by the nonlocal Timoshenko beam theory (TBT). The effects of nonlocal parameter, vibrational modes, length, and elastic medium on the nonlinear frequency of SWBNNTs are considered.     

The use of direct inverse maps to solve material identification problems: pitfalls and solutions

Material parameter identification is a technique that is used to calibrate material models, often a precursor to perform an industrial analysis. Conventional material parameter identification methods estimate the material parameters for a material model by solving an optimisation problem. An alternative but lesser-known approach, called a direct inverse map, directly maps the measured response to the parameters of a material model. In this study we investigate the potential pitfalls of the well-known stochastic noise and lesser-known model errors when constructing direct inverse maps. We show how to address these problems, explaining in particular the importance of projecting the measured response onto the domain of the simulated responses before mapping it to the material parameters. This paper concludes by proposing partial least squares regression as an elegant and computationally efficient approach to address stochastic and systematic (model) errors. This paper also gives insight into the nature of the inverse problem under consideration.     

A closed-loop supply chain configuration considering environmental impacts: a self-adaptive NSGA-II algorithm

Applied Intelligence - Configuration of a supply chain network is a critical issue that contributes to choose the best combination for a set of facilities in order to attain an effective and...     

Reinforcement effect of nanocellulose on thermal stability of nitrile butadiene rubber (NBR) composites

Poor physical and chemical attraction between nitrile butadiene rubber (NBR) matrix and filler resulted in low thermal properties. Therefore, nanocrystalline cellulose (NCC) as a reinforcement agent was used to increase the heat resistance and thermal stability of NBR composites. The addition of 2 phr NCC increased thermal stability and activation energy of NBR up to 75%. Meanwhile, the storage modulus of composites increased by 12 GPa at the similar loading of NCC. Good interfacial bonds of electrostatic interactions, formation of hydrogen bonds, crystallinity and nanosized of NCC are the main factors contribute to the final properties of NBR/NCC composites. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46594.     

Experimental Investigation and Artificial Neural Network Modeling of Warm Galvanization and Hardened Chromium Coatings Thickness Effects on Fatigue Life of AISI 1045 Carbon Steel

Journal of Failure Analysis and Prevention - In the present study, the main purpose is investigation of the coatings thickness effect on the fatigue life of AISI 1045 steel. Herein, two different...     

Characterisation of spray‐dried microparticles containing iron coated by pectin/resistant starch

Iron is one of three major minerals in human body. However, the iron deficiency is a medical problem in developed and underdeveloped countries due to its poor oral absorption or insufficient iron intake. Encapsulation could solve problems associated with oral iron consumption. Various advantages including low cost, biodegradability, biocompatibility and large‐scale production have been included in the current study. In a modified encapsulation method, iron microparticles were prepared using low methoxy pectin and resistant starch during spray drying. Covalent and hydrogen bonds were formed between iron and pectin and between polymers, respectively. Particles sized 3.5 ± 1.14 μm and showed spherical shapes. The yield of particles was 72.07%, and solubility and loading efficiency were 33.64% ± 0.88 and 34.79%, respectively. In conclusion, using iron as a cross‐linker of pectin molecules resulted in microparticles with appropriate properties of lowering organoleptic changes and a better bioavailability especially in dairy‐based products for food fortification.     

Novel high-performance nanocomposite proton exchange membranes based on poly (ether sulfone)

In the present research, proton exchange membranes based on partially sulfonated poly (ether sulfone) (S-PES) with various degrees of sulfonation were synthesized. It was found that the increasing of sulfonation degree up to 40% results in the enhancement of water uptake, ion exchange capacity and proton conductivity properties of the prepared membranes to 28.1%, 1.59 meq g⁻¹, and 0.145 S cm⁻¹, respectively. Afterwards, nanocomposite membranes based on S-PES (at the predetermined optimum sulfonation degree) containing various loading weights of organically treated montmorillonite (OMMT) were prepared via the solution intercalation technique. X-ray diffraction patterns revealed the exfoliated structure of OMMT in the macromolecular matrices. The S-PES nanocomposite membrane with 3.0 wt% of OMMT content showed the maximum selectivity parameter of about 520,000 S s cm⁻³ which is related to the high conductivity of 0.051 S cm⁻¹ and low methanol permeability of 9.8 × 10⁻⁸ cm² s⁻¹. Furthermore, single cell DMFC fuel cell performance test with 4 molar methanol concentration showed a high power density (131 mW cm⁻²) of the nanocomposite membrane at the optimum composition (40% of sulfonation and 3.0 wt% of OMMT loading) compared to the Nafion^®117 membrane (114 mW cm⁻²). Manufactured nanocomposite membranes thanks to their high selectivity, ease of preparation and low cost could be suggested as the ideal candidate for the direct methanol fuel cell applications.     

Uniform Cooling of a Flat Surface by an Optimized Array of Turbulent Impinging Air Jets

Abstract

The aim of this study is to investigate the uniform cooling of a hot isothermal heated target surface, using four turbulent impinging air jets. Eight parameters including the width of jets, the space between the inner jets, the space between inner and outer jets, the distance of jets from the plate, the impingement angle of jets, and the overall volumetric flow rate of the cooling air per unit depth of the nozzle are considered as design variables. The normalized standard deviation of the local Nusselt number from the desired Nusselt number is considered as the objective function. An optimization algorithm based on pattern search method is utilized to obtain the optimum array of the jets. Two different scenarios of the problem are considered, one with fixed normal impingement angles and the other with the optimized angles. Results show an almost uniform distribution of the local Nusselt number. Increasing the amount of desired Nusselt number for the case with fixed impinging angles results in a higher Reynolds number, a wider opening for outer jets and a reduction in jet to jet and jet to surface distances. However, changes in design parameters for the case with optimum impinging angles are erratic.