Properties of Nafion Under Uniaxial Loading at Different Temperatures: A Molecular Dynamics Study

Nafion membrane encounters many different thermal conditions and mechanical loadings because of its wide range of applications as a proton exchange membrane (PEM). Molecular dynamics simulation of hydrated Nafion at different temperatures is carried out to investigate the alteration of the physical properties of Nafion under uniaxial loading over a wide range of temperatures. According to the simulation results, increase of the temperature reduces the yield stress. The results also show that the polymer chains ordering increases the glass transition temperature and enhances the self-diffusion coefficient of water in hydrated Nafion. Comparisons show that the elastic modulus and viscosity coefficient obtained from the simulations at different temperatures are qualitatively in agreement with the measured values from experiments.     

Trends and challenges of biopolymer-based nanocomposites in food packaging

The ultimate goal of new food packaging technologies, in addition to maintaining the quality and safety of food for the consumer, is to consider environmental concerns and reduce its impacts. In this regard, one of the solutions is to use eco-friendly biopolymers instead of conventional petroleum-based polymers. However, the challenges of using biopolymers in the food packaging industry should be carefully evaluated, and techniques to eliminate or minimize their disadvantages should be investigated. Many studies have been conducted to improve the properties of biopolymer-based packaging materials to produce a favorable product for the food industry. This article reviews the structure of biopolymer-based materials and discusses the trends and challenges of using these materials in food packaging technologies with the focus on nanotechnology and based on recent studies.     

Role of turmeric in oxidative modulation in end‐stage renal disease patients

Oxidative stress is considered as a major player in uremia‐associated morbidity and mortality in hemodialysis (HD) patients. The aim of this study was to evaluate the effects of turmeric on oxidative stress markers in HD patients. This study was a prospective and double‐blind randomized clinical trial. Fifty HD patients aged 18–60 years were recruited after fulfilling the inclusion criteria. Patients were randomly categorized into 2 groups: trial group received turmeric and control group received placebo for 8 weeks. Each patient in the trial group received turmeric, whereas the control group received starch for the same 8 weeks. Plasma malondialdehyde (MDA), red blood cell (RBC) antioxidant enzyme activities as glutathione peroxidase (GPX), glutathione reductase (GR), and catalase (CAT), cholesterol, high‐density lipoprotein‐cholesterol, low‐density lipoprotein‐cholesterol, triglyceride, albumin, and hemoglobin were also measured before and after study. Although MDA level was reduced in both groups, the ratio of decrease was significantly higher in the turmeric group (0.2 vs. 0.1, P = 0.040). Three enzymes of GPX, GR, and CAT levels were increased in both groups; the ratio of increased was significantly higher in the turmeric group for the CAT enzyme (0.73 vs. 0.54; P = 0.02). Also, significant elevation of albumin level in the turmeric group compared with the control group was observed (P = 0.001). Regular ingestion of turmeric reduces plasma MDA and increases RBC CAT activity and plasma albumin levels in HD patients. Turmeric showed no adverse effects.     

Selective adsorption of ketoconazole from aqueous solutions using a new molecularly imprinted polyurethane coated magnetic multiwall carbon nanotubes

New magnetic molecularly imprinted polyurethanes based on magnetic multi-walled carbon nanotubes (MMWNTs-MIPUs) were synthesized with specific selectivity toward ketoconazole (KTZ) as an anti-fungal drug. First, novel N-(4-carboxyphenyl) trimellitimide diisocyanate (NTDIS) was prepared from the reaction of trimellitic anhydride and 4-amino benzoic acid in two steps. Then, NTDIS was functionalized by β-cyclodextrin and methacrylic acid (MAA-NTDIS-β-CD). MAA-NTDIS-β-CD was used as a functional monomer, KTZ as a template, ethylene glycol dimethacrylate (EGDMA) as a cross-linking agent and 2,2′-azobisisobutyronitrile (AIBN) as initiator. Structure and properties of the prepared compounds were characterized by FTIR, ¹H NMR, FESEM, XRD, VSM, BET, and EDX. The influence of parameters such as solution pH, contact time, temperature, and initial concentrations in controlled absorption of KTZ using MMWCNTs-MIPU and MMWCNTs-NIPU were evaluated. The kinetic data were measured using the pseudo-first-order and pseudo-second-order equation. The pseudo-second-order equation displayed the best fit for the kinetic studies (R² 0.9958). The adsorption equilibrium of KTZ using MMWCNTs-MIPU could be well-defined with the Langmuir isotherm model, and the maximum adsorption capacity was calculated as 52.35 mg g^–1. The prepared MMWCNTs-MIPU can be simply separated by an external magnetic field and, MMWCNTs-MIPU can be used after six filtration-regeneration cycles.

     

Hydrothermal synthesis and structural studies of a new coordination polymer of lanthanum(Ⅲ) with benzene-1,2,4,5-tetracarboxylic acid and 4,4''-bipyridine

A new lanthanum complex formulated as { (bpyH2)[La(btc)(H2O)4(NO3)]·2H2O }n (1) (btcH4=benzene-1,2,4,5-tetracarboxylic acid; bpy=4,4'-bipyridine) was hydrothermally synthesized. The complex was characterized by FT-IR spectroscopy, elemental analysis and X-ray diffraction. X-ray crystal structural analysis revealed that the compound belonged to the monoclinic space group C2/c with cell parameters a= 1.42806(7) nm, b=1.10258(5) ran, c=-1.60333(8) nm and β=101.9400(10)°. The complex was polymeric with La<Ⅲ atoms linked by four O atoms from two carboxylate groups of one benzene-1,2,4,5-tetracarboxylate. The LaⅢ atom was ten coordinated in a distorted tetracapped trigonal prism. In the crystal structure, a wide range of noncovalent interactions consisting of hydrogen bonding (of the types of O-H…O, N-H…O and C-H…O) and ion pairing interactions connected the various components into a supramolecular structure.     

Deep convolution network for surveillance records super-resolution

Multimedia Tools and Applications - The aim of image super resolution (SR) is to recover low resolution (LR) input image or video to a visually desirable high-resolution (HR) one. The task of...     

Deep semantic preserving hashing for large scale image retrieval

Multimedia Tools and Applications - Hashing approaches have got a great attention because of its efficient performance for large-scale images. This paper, aims to propose a deep hashing method...     

Measurement and modeling of solubility of H2S in aqueous diisopropanolamine solution

Modeling of solubility of acid gases in aqueous alkanolamine solutions is essential for design of an absorber for natural gas sweetening. In this work an apparatus similar to the device of Hayduk and Chen (1970), which was improved by Pahlavanzadeh and Motahhari (1997), for the measurement of gas solubility data by the synthetic method was used. The solubility of hydrogen sulfide in aqueous diisopropanolamine (DIPA) solution in mass concentration range of 30–40% for 101,325 Pa pressure and for temperature ranging from 313–343 K was reported. The obtained experimental solubility data of H₂S in aqueous solutions of DIPA was used to predict the different interaction parameters of modified UNIQUAC-NRF model for calculating the activity coefficients. For nonideality of species in liquid phase, the UNIQUAC-NRF equation with ion-pair approach was applied. For long range interaction, the Pitzer-Debye-Huckel term was used.