Self‐healing imidazolium‐based ionene‐polyamide membranes: an experimental study on physical and gas transport properties

A new series of six imidazolium‐based ionenes containing aromatic amide linkages has been developed. These ionene‐polyamides are all constitutional isomers varying in the regiochemistry of the amide linkages (para, meta) and xylyl linkages (ortho, meta, para) along the polymer backbone. The physical properties as well as the gas separation behaviors of the corresponding membranes have been extensively studied. These ionene‐polyamide membranes show excellent thermal and mechanical stabilities, together with self‐healing and shape memory characteristics. Most importantly, [TC‐API(p)‐Xy][Tf₂N] and [IC‐API(m)‐Xy][Tf₂N] membranes (TC, terephthaloyl chloride; API, 1‐(3‐aminopropyl)imidazole; Xy, xylyl; Tf₂N, bis(trifluoromethylsulfonyl) imide; IC, isophthaloyl chloride), where the amide and xylyl linkages are attached at para and meta positions, exhibit superior selectivity for CO₂/CH₄ and CO₂/N₂ gas pairs. We also demonstrate the transport properties and diverse applicability of our newly developed ionene‐polyamides, particularly [TC‐API(p)‐Xy][Tf₂N], for various industrial applications. © 2019 Society of Chemical Industry     

Understanding the effects of backbone chemistry and anion type on the structure and thermal behaviors of imidazolium polyimide‐ionenes

Advancements in the performance and properties of ionenes can be achieved via rational molecular design strategies which combine structural elements of ionic liquids (ILs) and high‐performance polymers. The use of imidazole‐amine molecules with asymmetric reactivity has enabled the synthesis of new bis(imidazole) diimide monomers which are then polymerized via the Menshutkin reaction, followed by anion exchange to various molecular species well known in the IL literature. In this work, three types of imidazolium polyimide‐ionene backbones were synthesized starting from 1‐(3‐aminopropyl)imidazole and pyromellitic dianhydride (PMDA) or 4,4′‐(hexafluoroisopropylidene)diphthalic anhydride (6FDA) or from 1‐(4‐aminophenyl)imidazole and 6FDA, with these monomers then reacted with para‐dichloroxylene. The Cl^? anions on the resultant ionenes were then exchanged with one of six molecular anions yielding a total of 18 distinct polymer compositions. The functional groups present within the cationic backbone as well as the anion type were observed to strongly influence both the thermal and organizational properties of these new ionenes. © 2019 Society of Chemical Industry     

Influence of pH and Temperature on Structural,Optical and Catalytical Investigations of CeO2-SiO2 Nanoparticles

Silicon - CeO2-SiO2 nanoparticles were synthesized by surfactant assisted via sol-gel process at variable pH 9, 10 and 11 by keeping constant temperature of...     

Antibacterial responses of zinc oxide structures against Staphylococcus aureus, Pseudomonas aeruginosa and Streptococcus pyogenes

The antibacterial responses of zinc oxide (ZnO) structures against Staphylococcus aureus, Pseudomonas aeruginosa, and Streptococcus pyogenes were investigated. Two ZnO powder samples, one with rod-like (ZnO-1) and the other with plate-like (ZnO-2) structures, were characterized for their morphological, structural, and optical properties. The rods were 30–120 nm in diameter, and the plates were 40–100 nm thick. XRD results revealed the wurtzite crystallinity of ZnO with average crystallite sizes of 33.72 (ZnO-1) and 39.25 (ZnO-2) nm. ZnO-2 possessed a relatively higher green photoluminescence than that of ZnO-1, suggesting a relatively higher amount of oxygen vacancies in ZnO-2 structures. Optical density measurements showed that both ZnO samples inhibited the growth of S. aureus, P. aeruginosa, and S. pyogenes by 29–98% after 24 h of treatment. The most dramatic growth inhibition was observed in S. pyogenes with 96% and 98% inhibition for ZnO-1 and ZnO-2, respectively, leading to a probable bactericidal phenomenon. The toxicological effect on S. pyogenes was probably due to the absence of catalase, making the bacteria vulnerable to the harmful reactive oxygen species (ROS) released by ZnO. ZnO-1 induced higher inhibition toward S. aureus and P. aeruginosa than that of ZnO-2 because of the smaller particle size of rod structures compared to plate and slab structures. The adhesion of ZnO particles on the membrane of bacteria could be the underlying cause of zinc toxicity effect towards the bacteria. ZnO-1 possessed larger surface area and provided higher amount of zinc atom, thereby inducing higher level of toxicity toward the bacteria. Two possible mechanisms were proposed to explain the inhibition of bacteria, namely, ROS toxicity toward cellular constituents and interaction of zinc with bacteria membrane through adhesion of ZnO particle. Several ZnO morphological-antibacterial correlations were presented in this work.     

A Novel Hybrid Machine Learning Approach for Classification of Brain Tumor Images

Abnormal growth of brain tissues is the real cause of brain tumor. Strategy for the diagnosis of brain tumor at initial stages is one of the key step for saving the life of a patient. The manual segmentation of brain tumor magnetic resonance images (MRIs) takes time and results vary significantly in low-level features. To address this issue, we have proposed a ResNet-50 feature extractor depended on multilevel deep convolutional neural network (CNN) for reliable images segmentation by considering the low-level features of MRI. In this model, we have extracted features through ResNet-50 architecture and fed these feature maps to multi-level CNN model. To handle the classification process, we have collected a total number of 2043 MRI patients of normal, benign, and malignant tumor. Three model CNN, multi-level CNN, and ResNet-50 based multi-level CNN have been used for detection and classification of brain tumors. All the model results are calculated in terms of various numerical values identified as precision (P), recall (R), accuracy (Acc) and f1-score (F1-S). The obtained average results are much better as compared to already existing methods. This modified transfer learning architecture might help the radiologists and doctors as a better significant system for tumor diagnosis.     

Nanosilver Mitigates Biofilm Formation via FapC Amyloidosis Inhibition

Multidrug resistance of bacteria is a major challenge due to the wide‐spread use of antibiotics. While a range of strategies have been developed in recent years, suppression of bacterial activity and virulence via their network of extracellular amyloid has rarely been explored, especially with nanomaterials. Here, silver nanoparticles and nanoclusters (AgNPs and AgNCs) capped with cationic branched polyethylenimine polymer are synthesized, and their antimicrobial potentials are determined at concentrations safe to mammalian cells. Compared with the ultrasmall AgNCs, AgNPs entail stronger binding to suppress the fibrillization of FapC, a major protein constituent of the extracellular amyloid matrix of Pseudomonas aeruginosa. Both types of nanoparticles exhibit concentration‐dependent antibiofilm and antimicrobial properties against P. aeruginosa. At concentrations of 1 × 10^?6 m or below, both the bactericidal activity of AgNCs and the antibiofilm capacity of AgNPs are associated with their structure‐mediated bio–nano interactions but not ion release. For AgNPs, specifically, their antibiofilm potency correlates with their capacity of FapC fibrillization inhibition, but not with their bactericidal activity. This study demonstrates the antimicrobial potential of safe nanotechnology through the novel route of amyloidosis inhibition.     

On Bayesian EWMA control charts under different loss functions

The motivation for this study is to analyze Bayesian exponentially weighted moving average (EWMA) control chart under 3 loss functions namely, SELF, LLF, and PLF. Informative priors (normal and mixture of normal) and non‐informative priors (Uniform and Jefferys) are considered for the analysis. The performance of Bayesian EWMA control chart using posterior and posterior predictive distribution scheme has been evaluated using average run length (ARL) and standard deviation run length (SDRL) as performance measures. Monte Carlo simulations are used to compute the performance measures for different values of smoothing constant. An illustrative example is also presented for practical considerations of Bayesian EWMA control chart.     

Optimization of nutraceutical coenzyme Q10 nanoemulsion with improved skin permeability and anti-wrinkle efficiency

Coenzyme Q10 (CoQ10) is an insoluble, poorly permeable antioxidant with great biological value which acts as anti-aging and anti-wrinkle agent. To improve its permeability through topical application, the current study aimed at formulating oil/water (o/w) nanoemulsion (NE) as an efficient vehicle for delivering (CoQ10) through the skin barriers. The solubility of (CoQ10) was tested for various oils, surfactants (S), and co-surfactants (CoS). The NE region was determined by constructing pseudoternary phase diagrams. NE formulae containing 1, 2, and 3% w/w drug have been subjected to thermodynamic stability test. The formulae that passed thermodynamic stability tests were characterized by physical properties as pH, viscosity, refractive index, droplet size, zeta-potential, TEM, electroconductivity, in vitro release, and ex vivo permeation. The formula ‘F2’ containing 10% w/w isopropyl myristate (oil phase), 60% w/w of Tween 80: Transcutol HP mixture (S/CoS_mix) at ratio 2:1, 30% w/w water and 2% w/w drug was evaluated for its anti-wrinkle efficiency using an animal model. The ‘F2’ formula showed 11.76?±?1.1?nm droplet size, 1.4260?±?0.0016 refractive index, 0.228 PDI, ?14.7?±?1.23?mv zeta potential, 7.06?±?0.051?pH, 199.05?±?0.35?cp viscosity, and the highest percentage of drug release in the selected dissolution media. About 47.21% of the drug was released in phosphate buffer 7.4 containing 5% w/v Labrasol and 5% w/v isopropyl alcohol through 24?h. It also showed the highest drug flux (J_ss?=?3.164?µg/cm²/h), enhancement ratio (E_r?=?8.32), and permeability coefficient (K_p?=?22.14?×?10^?4 cm²/h). CoQ10 NE reduced the skin wrinkles and gave the skin smooth appearance. Our investigation suggests the potential use of NE as a vehicle for enhancing solubility and permeability of CoQ10 and thus improving its anti-wrinkle efficiency.     

Méthode améliorée d'analyse dite du volume réduit

La méthode dite du «volume réduit» pour déterminer le dosage en ciment des éprouvettesde mortier ou de béton durci présente des inconvénients certains. Les auteurs décrivent, dans cet article, des améliorations apportées à I'appareillage qui ont permis des relevés d'une précision plus constante, allantjusqu'à 0,01 cm du volume de matière inerte demeurant après les procédures d'essai du VR habituelles.     

Carriers-mediated ferromagnetic enhancement in Al-doped ZnMnO dilute magnetic semiconductors

Nano-crystalline Zn_{0.95 – x}Mn_0.05Al_xO (x = 0, 0.05, 0.10) dilute magnetic semiconductors (DMS) were synthesized by sol–gel derived auto-combustion. X-ray diffraction (XRD) analysis shows that the samples have pure wurtzite structure typical of ZnO without the formation of secondary phases or impurity. Crystallite sizes were approximated by Scherrer formula while surface morphology and grain sizes were measured by field emission scanning electron microscopy. Incorporation of Mn and Al into the ZnO structure was confirmed by energy-dispersive X-ray analysis. Temperature dependent electrical resistivity measurements showed a decreasing trend with the doping of Al in ZnMnO, which is attributable to the enhancement of free carriers. Vibrating sample magnetometer studies confirmed the presence of ferromagnetic behavior at room temperature. The results indicate that Al doping results in significant variation in the concentration of free carriers and correspondingly the carrier-mediated magnetization and room temperature ferromagnetic behavior, showing promise for practical applications. We attribute the enhanced saturation magnetization and electrical conductivity to the exchange interaction mediated by free electrons.