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关键词： Aniline  

摘要： In this study, a new polyaniline (PANI) derivative, poly[2-(cyclohex-2-en-1-yl)aniline], was synthesized for the first time. It was shown by varying the synthetic parameters that the highest polymer yield was obtained if HNO3 and (NH4)(2)S2O8 were used. It was found that variation in the conditions for synthesizing poly[2-(cyclohex-2-en-1-yl)aniline] resulted in changes in the optical properties, for example, the PANI derivative obtained in HClO4 medium and in the presence of (NH4)(2)S2O8 demonstrated the highest luminescence quantum yield (0.05). Using thermogravimetric analysis of poly[2-(cyclohex-2-en-1-yl)aniline], the main three stages of the polymer thermal degradation were identified. Processing of thermogravimetric curves allowed us to calculate the kinetic and thermodynamic parameters of the thermal degradation of the polymer at various heating rates. The use of poly[2-(cyclohex-2-en-1-yl)aniline] as a sensitive material in resistive sensors showed a high response of electrical conductivity to the changes in humidity (% RH) and ammonia concentration in the environment. The presented results demonstrate an efficient method for PANI modification that favors an improvement in solubility, appearance of photoluminescent properties, and broadening the practical application.

关键词： Controlled release   peripheral nervous system   sericin  

摘要： Peripheral nerve injuries may lead to a significant function loss, which deeply affect patient's quality of life. In this context, tissue engineered collagen-based nerve guides are a promising alternative to autografts. To enhance the regeneration of the injured nerve tract, several bioactive molecules can be adopted as further components of the collagen-based conduits. Herein, sericin (Ser), a waste product of textile industry, was combined with type I collagen (Col), for the development of a bioactive substrate potentially able to support and enhance the regeneration of the peripheral nervous system. In particular, in order to identify an optimal substrate composition in terms of physicochemical and biological properties, thin Ser-Col films with different Ser:Col ratios were produced by air-drying and subsequently crosslinked through two different crosslinking methods. Then, Ser:Col films were characterized from a physicochemical point of view by examining secondary protein structure modifications via FTIR spectroscopy, swelling ratios, degradation rates and Ser release kinetics. Moreover, Ser:Col films ability to promote adhesion and proliferation of Schwann cells was evaluated in vitro. The results obtained in this study, although preliminary, suggest that Ser:Col blends could represent a promising strategy to enhance the repair of damaged peripheral nerves, by providing a sustained release of Ser from collagen-based nerve substrates.

关键词： Chitosan   freeze-drying   microwave-assisted gas foaming   solvent casting   stabilization  

摘要： In this study, the aim was to investigate the changes in the physical, chemical and biological properties of chitosan scaffolds obtained by freeze-drying and microwave-assisted gas foaming methods. Also, it was aimed to determine the most suitable one when scaffolds are subjected to different stabilization processes. To prevent the solubility of chitosan scaffolds, stabilization processes were carried out by treatment with ethanol (EtOH), sodium hydroxide (NaOH), or sodium bicarbonate (Na2CO3). The chemical and physical changes in the chitosan structure induced by different stabilization methods were investigated by characterization studies carried out comparatively with two-dimensional chitosan films. The results showed that, particularly, NaOH stabilization improved the physical, thermal, and mechanical properties of the bulk material. The wettability and surface roughness of the chitosan films were enhanced for cellular adhesion after stabilization. Cell culture studies revealed that variations in both fabrication and stabilization methods significantly affected in vitro cellular responses such as cell attachment, proliferation and viability. In conclusion, chitosan scaffolds fabricated by microwave-assisted gas foaming and stabilized by NaOH solution were found as the best structure due to their higher cellular activities.

关键词： Carbohydrates   Bacteria   Dynamic light scattering   Fungi   Polymers  

摘要： Extracellular polysaccharides are widely produced by bacteria, yeasts, and algae. These polymers are involved in several biological functions, such as bacteria adhesion to surface and biofilm formation, ion sequestering, protection from desiccation, and cryoprotection. The chemical characterization of these polymers is the starting point for obtaining relationships between their structures and their various functions. While this fundamental correlation is well reported and studied for the proteins, for the polysaccharides, this relationship is less intuitive. In this paper, we elucidate the chemical structure and conformational studies of a mannan exopolysaccharide from the permafrost isolated bacterium Psychrobacter arcticus strain 273-4. The mannan from the cold-adapted bacterium was compared with its dephosphorylated derivative and the commercial product from Saccharomyces cerevisiae. Starting from the chemical structure, we explored a new approach to deepen the study of the structure/activity relationship. A pool of physicochemical techniques, ranging from small-angle neutron scattering (SANS) and dynamic and static light scattering (DLS and SLS, respectively) to circular dichroism (CD) and cryo-transmission electron microscopy (cryo-TEM), have been used. Finally, the ice recrystallization inhibition activity of the polysaccharides was explored. The experimental evidence suggests that the mannan exopolysaccharide from P. arcticus bacterium has an efficient interaction with the water molecules, and it is structurally characterized by rigid-rod regions assuming a 14-helix-type conformation.

关键词： Technological processing   molecular structure   vibrational spectroscopy   nutrient metabolism   modeling   cool-season Vicia faba  

摘要： This review aims to update recent progress in processing induced molecular structure changes in the association of physicochemical structure properties with nutritional metabolism in cool-season faba bean (Vicia L.), which was revealed using advanced vibrational molecular spectroscopy in combination with chemometrics and advanced nutrient modeling techniques. The review focused on strategies to improve the utilization of the cool-season faba bean through heat-related technological treatments and the relationship of the processing induced molecular structural changes to nutrient delivery and metabolism in ruminant systems. The updated methods with truly absorption nutrient modeling techniques and advanced vibrational molecular spectroscopy techniques sourced by globar and synchrotron radiation (e.g. NIR, near Infrared, FTIR, Fourier transform infrared, DRIFT, diffuse reflectance infrared Fourier transform, ATR-FTIR, attenuated total reflectance-FTIR, FTIRM, FTIR micro-spectroscopy, SR-FTIRM, synchrotron radiation- FTIRM) to study cool-season faba bean were reviewed. This article provides an insight and a new approach on how to combine advanced nutrient modeling techniques with cutting-edge vibrational molecular spectroscopic techniques to study the processing induced molecular structure change in relation to molecular nutrition of cool-season Vicia faba as well as the interaction between molecular structure and molecular nutrition.

关键词： PFAS   Surfactants   Air-water interface   Surface tension   Standard free energy of adsorption   Interfacial partition coefficient   Multimedia model  

摘要： The factors controlling per- and polyfluoroalkyl substances (PFAS) environmental fate remains the subject of considerable debate and study. As surfactants, PFAS readily partition to interfaces, a property that controls their transport and fate. A group contribution model is developed to predict the extent to which PFAS partitions to the air-water interface. Langmuir adsorption and Szyszkowski equation parameters were fitted to literature air-water surface tension data for a range of PFAS and conventional hydrocarbon surfactants. This approach enabled the prediction of the impact of the hydrophilic head group, and other molecular components, on PFAS interfacial partitioning in instances when PFAS data are unavailable but analogous hydrocarbon surfactant data are available. The model was extended to predict a range of parameters (i.e., solubility, critical micelle concentration (CMC), K-D, K-oc and K-ow) that are used to predict PFAS environmental fate, including long-range PFAS transport and in multimedia models. Model predictions were consistent with laboratory and field derived parameters reported in the literature. Additionally, the proposed model can predict the impact of pH and spedation on the extent of PFAS interfacial partitioning, a potentially important feature for understanding the behaviors of some ionizable PFAS, such as fluorinated carboxylic adds. The proposed model provides a conceptually straightforward method to predict a wide range of environmental fate parameters for a wide range of PFAS. As such, the model is a powerful tool that can be used to determine parameters needed to predict PFAS environmental fate. (C) 2020 Elsevier B.V. All rights reserved.

关键词： Tetracycline   Absorption   In-situ electrocatalysis   Energy consumption   Degradation mechanism   Degradation pathways  

摘要： Novel particle electrodes, i.e. flotation tailings particle electrode (FPE), were prepared using flotation tailings, garden soil, and soluble starch with a mass ratio of 16:3:1, and then used in tetracycline wastewater treatment. The physicochemical properties of FPE were systematically characterized using SEM, XRD, FT-IR and XRF. Tetracycline adsorption and its adsorption mechanism onto FPE was explored for the first time. Parameters affecting FPE's degradation efficiency and energy consumption such as current density, electrolysis time, initial concentration, initial pH and aeration rate were examined. The electrocatalytic degradation of tetracycline shows that the degradation of tetracycline meets the pseudo-first-order kinetics. Moreover, the numbers of center dot OH produced on the surfaces of the cathode, anode and particle electrode were compared. Results showed that the adsorption-saturated FPE can be regenerated by electrochemical action to induce further absorption and form in situ electrocatalysis. In order to find out the transformation products in water and degradation pathways of Tetracycline, UHPLC method was used to obtain the degradation pathways for Tetracycline. So, this work could provide a fabrication of high-efficiency and low-cost electrocatalytic for removal of pharmaceuticals pollutants from waste water as well as deeper insight into electrocatalytic mechanism, transformation products, and degradation pathways of Tetracycline in water.

关键词： Gemini surfactant   BSA   Interaction   Fluorescence quenching   Molecular modeling  

摘要： To study the interaction of the series of pyridinium based gemini surfactants (GS) (referred to as m-Py-m, m = 14, 16);4,4'-(propane-1,3-diyl)bis(1-(2-(tetradecyloxy)-2-oxoethyl) dipyridinium chloride (14-Py-14), and 4,4'-(propane-1,3-diyl) bis(1-(2-(hexadecyloxy)-2-oxoethyl)dipyridinium chloride (16-Py-16) with bovine serum albumin (BSA), various physicochemical and spectroscopic tools such as tensiometry, steady-state fluorescence, synchronous fluorescence, pyrene fluorescence, UV-visible, far-UV circular dichroism (CD) were utilized at physiological pH (7.4) and 298 K in combination with computational molecular modeling analysis. The tensiometric results show significant modifications in interfacial and thermodynamic parameters for m-Py-m GS upon BSA combination, deciphering the gemini surfactant-BSA interaction. Steady-state fluorescence analysis evaluates the structural alterations of BSA with the addition of m-Py-m GS. The plots of Stern-Volmer, modified Stern-Volmer, and thermodynamic parameters were used to determine the binding type of m-Py-m GS to BSA. The synchronous fluorescence spectra state a mild effect of gemini surfactants on the emission intensity of tyrosine (Tyr) residues, on the other hand, tryptophan (Trp) residues showed a significant effect. Post addition of GS, the plot of pyrene fluorescence reveals the mild micropolarity fluctuations via the probe (pyrene) molecules encapsulated in BSA. UV-visible experiments support the complex formation between the BSA and m-Py-m GS. Far UV CD measurements revealed the modifications in the secondary structure of protein produced by m-Py-m GS. Furthermore, we also used the computational molecular modeling for attaining deep insight into BSA and m-Py-m GS binding and the results are supported with our experimental results. (C) 2020 Elsevier B.V. All rights reserved.

关键词： Diazene dye   Copper   Crystal structures   Hirshfeld surface   Polymer  

摘要： New binuclear copper(II) complex [Cu2L2] zig-zag coordination polymer (CCP) have been synthesized via one-pot copper(II) acetate/(E)-2-((2-hydroxynaphthalen-1-yl)diazenyl)benzoic dye through an in situ aqua doubly deprotonated ligand substitution reaction. The coordination polymer complex was characterized by spectroscopic and CHN-elemental analysis. The crystal structure has been specified by the XRD method exhibiting that the Cu(II) center geometry is with five-coordinated distorted tetragonal pyramidal. The desired CCP structure chains are connected into a 2D-Supramolecular assembly via one C-H...O H-bond and enhanced by a pi-pi stacking interactions. These interconnections strengthened the lattice of CCP that originated the formation of super thermal CCP complexes. The fundamental vibrational wavenumbers and electron transfer in the free ligand are combined with the complex before and after coordination to demonstrate the spectral behavior of L-2 in the desired zig-zag CCP. The 2D-fingerprint (2D-FP) and Hirshfeld surface analysis (HSA) computations were served to prove the 2D-network packed crystal lattice interactions. (C) 2020 Elsevier B.V. All rights reserved.

关键词： Metal complexes   Benzoylthiourea ligands   Thermal analysis   Single crystal X-ray crystallography  

摘要： A series of Fe(III), Co(III), Ni(II), Cu(II), Zn(II) and In(III) N-morpholine-N'-benzoylthiourea complexes have been synthesised and characterised by elemental analysis, thermal analysis, infrared spectroscopy, H-1 nuclear magnetic resonance spectroscopy and single crystal X-ray crystallography. Thermogravimetric analysis shows that all the complexes undergo a two-step decomposition process except for the iron(III) complex and the indium(III) complexes, which show three-step and one-step decompositions, respectively. The complexes are thermally stable up to approximately 300 degrees C. The ligand coordinates the various metal ions in a bidentate (L-kO,S) chelating mode, facilitated by deprotonation of the acidic amide (-C(O) N'HC (S)) moiety. This mode of coordination allows for the facile formation of neutral bis/tris-6-membered chelates of type [M(L-kS,O)(x)] where x = 2 or 3 for divalent or trivalent metal ions, respectively. (C) 2020 Elsevier B.V. All rights reserved.