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关键词： Bloating activation temperature   Lightweight aggregate   Black core   MIP   Aeration rate  

摘要： This study investigated the effect of the aeration rate of molded pellets on the physical and chemical bloating mechanisms of artificial lightweight aggregate materials. Samples were prepared by mixing acid clay as a raw material with Fe2O3 and carbon. The samples were manufactured by various molding methods, in this case hand molding, uniaxial pressure molding, cold isostatic pressure molding, and extrusion molding. The particle density and pore distribution of the molded pellets were confirmed, and the changes in the properties and bloating activation temperatures of the aggregates were observed. The density of each molded pellet differed according to the molding method, and it was confirmed that molded pellets having a lower aeration rate bloated at a lower temperature. When the pressure from the gas inside is high at a temperature where viscous behavior does not occur, cracks form inside the aggregate. In the samples to which Fe2O3 and C were added, the internal viscous behavior did not cause cracking due to due to the formation of black cores. In the molded pellets with low aeration rates, the black core formed at a lower temperature, and the bloat-promoting effect was confirmed. (C) 2020 Elsevier Ltd. All rights reserved.

关键词： Amorphous   Co-amorphous   Crystallization   Dissolution   Naproxen   Raman spectroscopy   UV imaging  

摘要： Co-amorphous systems comprising low-molecular weight drugs and co-formers constitute an interesting approach to optimize pharmaceutical performance of drugs with low aqueous solubility. Within the different types of co-amorphous systems, the combination of a drug with its own salt may be an attractive formulation option due the absence of any inactive co-formers. The aim of this study was to investigate the possibility of forming a co-amorphous system from naproxen (NAP) and its sodium salt (NAP(Na)). Ball milling of NAP and NAP(Na) at equal molar ratio resulted in the formation of a co-amorphous system whilst NAP and NAP(Na) alone were crystalline following both, ball milling and melt quenching. Infrared spectroscopy and physical stability testing revealed that intermolecular interactions were able to maintain the ball milled NAP-NAP(Na) system amorphous for 2 months at 40 degrees C. Surprisingly, the dissolution rate of co-amorphous NAP-NAP(Na) was only intermediate between those of crystalline NAP and crystalline NAP(Na). In situ Raman spectroscopic measurements indicated an initial phase separation of the co-amorphous form to NAP and NAP(Na) followed by dissociation of sodium from NAP(Na) and crystallization to NAP. These findings contribute to the design of co-amorphous formulations with the combination of a drug and its own salt.

关键词： Drug discovery   Molecules   Assays   Solubility   Permeability  

摘要： The rule of 5 was designed to estimate the likelihood of poor absorption or permeation, noting the impact of poor solubility. This Perspective explores the impact of various physicochemical descriptors and contemporary lipophilicity measurements on permeability and solubility, showing that the distribution coefficient log D-7.4 (rather than log P) is the most impactful parameter. Molecular weight, almost invariably the defining characteristic of "beyond the rule of 5" compounds, has little impact on solubility when log D-7.4 measurements and aromaticity are considered. Predicting permeation is more complex, given passive and carrier transport mechanisms;however, notable patterns of behavior are apparent, giving insight even "beyond the rule of 5". Recommended best practices should involve using the facts (measurements) and the patterns they reveal to establish informative principles rather than fastidious rules.

关键词： Hydrocarbons   Anions   Catalysts   Oxidation   Perovskites  

摘要： LaFeO3 perovskites, obtained through co-precipitation of carbonates with (NH4)(2)CO3, co-precipitation of hydroxides with NaOH, citrate method, and through solid-state reaction using metal nitrates as precursors, were deposited on a heat-resistant foil support. Their physicochemical properties were determined by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), differential scanning calorimetry and thermogravimetric analysis (DSC/TGA), and specific surface area measurements. DSC/TGA showed that phase transitions took place in the LaFeO3 perovskite up to 800-840 degrees C. Pure LaFeO3 perovskite phase was obtained only when the citrate method was used. The following decreasing order of methane and hexane oxidation activity at 700 degrees C was determined for the catalysts with the LaFeO3 perovskite obtained by different methods: citric acid > ammonium carbonate similar to metal nitrates > sodium hydroxide. LaFeO3 catalysts obtained at 700 degrees C in the presence of citric acid or ammonium carbonate can be used as three-way automotive exhaust catalysts or as catalysts in environmental protection.

关键词： Plastics   Cyclization   Chemical structure   Indoles   Polymers  

摘要： Intramolecular acid-catalyzed cyclization was suggested for the first time for a polyaniline derivative, namely, poly[2-(2-chloro-1-methylbut-2-en-1-yl)aniline] (PClPA), to give hitherto unknown poly(2-ethyl-3-methylindole) (2E3MPIn) in a high yield (81%). This is the first example of synthesizing a polymer of the indole series with 1,5-addition of monomeric units that are incorporated into the polymer structure. The physicochemical properties of the new polymer were studied. Its structure was confirmed by spectral methods and quantum-chemical calculations. The 2E3MPIn polymer showed good thermal stability compared to the starting PClPA polymer. A study of the photoluminescence of polymers showed that the emission spectrum of 2E3MPIn demonstrated a bathochromic shift (16 nm) and a considerable increase in the luminescence intensity in comparison to PClPA. The 2E3MPIn sample was found to possess photoconductivity. Irradiation of the polymer film increases the electrical conductivity by a factor of 2. The electrochemical properties obtained from the UV-vis spectrum and cyclic voltammograms suggest that 2E3MPIn has good electroactivity. A sample of 2E3MIn demonstrates a fine porous structure resembling a "sponge". In addition, the PClPA and 2E3MPIn samples synthesized were used as sensitive materials in resistive moisture sensors. The 2E3MPIn polymer demonstrated a higher response than PClPA to changes in the environment humidity. The observed changes in the physicochemical properties of 2E3MPIn compared to PClPA confirm that the polyheterocyclization reaction occurs successfully and can be considered as an efficient way for synthesizing new functional polymers of the indole series.

关键词： Vesicles   Lipids   Membranes   Copolymers   Monolayers  

摘要： In the last few years, hybrid lipid-copolymer assemblies have attracted increasing attention as possible two-dimensional (2D) membrane platforms, combining the biorelevance of the lipid building blocks with the stability and chemical tunability of copolymers. The relevance of these systems varies from fundamental studies on biological membrane-related phenomena to the construction of 2D complex devices for material science and biosensor technology. Both the fundamental understanding and the application of hybrid lipid-copolymer-supported bilayers require thorough physicochemical comprehension and structural control. Herein, we report a comprehensive physicochemical and structural characterization of hybrid monolayers at the air/water interface and of solid-supported hybrid membranes constituted by 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and the block copolymer poly(butadiene-b-ethyleneoxide) (PBD-b-PEO). Hybrid lipid-copolymer supported bilayers (HSLBs) with variable copolymer contents were prepared through spontaneous rupture and fusion of hybrid vesicles onto a hydrophilic substrate. The properties of the thin films and the parent vesicles were probed through dynamic light scattering (DLS), differential scanning calorimetry (DSC), optical ellipsometry, quartz crystal microbalance with dissipation monitoring (QCM-D), and confocal scanning laser microscopy (CSLM). Stable, hybrid lipid/copolymer systems were obtained for a copolymer content of 10-65 mol %. In particular, DSC and CSLM show lateral phase separation in these hybrid systems. These results improve our fundamental understanding of HSLBs, which is necessary for future applications of hybrid systems as biomimetic membranes or as drug delivery systems, with additional properties with respect to phospholipid liposomes.

关键词： Cell culture   mechanical modulus   poly(glycerol sebacate)   salt templates   scaffold  

摘要： Poly(glycerol sebacate), PGS, is a biodegradable elastomer recently proposed in the form of scaffolds for cardiac, vascular, cartilage or neural applications. In the present work, several processing variables for the fabrication of PGS scaffolds by the salt fusion method were systematically studied, namely the pre-polymer/porogen ratio, the salt particles average size, use of tetrahydrofuran to dissolve the pre-polymer for its injection in the porogen template, and the curing pressure. The effect of these variables on their structural, mechanical and biological properties was assessed to select those leading to optimal ones in terms of their potential performance in tissue engineering applications. [GRAPHICS] .

关键词： Oxides   Nanoparticles   Cells   Agglomeration   Toxicity  

摘要： The concern about titanium dioxide nanoparticles (TiO2-NPs) toxicity and their possible harmful effects on human health has increased. Their biological impact is related to some key physicochemical properties, that is, particle size, charge, crystallinity, shape, and agglomeration state. However, the understanding of the influence of such features on TiO2-NP toxicity remains quite limited. In this study, cytotoxicity, proinflammatory response, and oxidative stress caused by five types of TiO2-NPs with different physicochemical properties were investigated on A549 cells used either as monoculture or in co-culture with macrophages differentiated from the human monocytic THP-1 cells. We tailored bulk and surface TiO2 physicochemical properties and differentiated NPs for size/specific surface area, shape, agglomeration state, and surface functionalization/charge (aminopropyltriethoxysilane). An impact on the cytotoxicity and to a lesser extent on the proinflammatory responses depending on cell type was observed, namely, smaller, large-agglomerated TiO2-NPs were shown to be less toxic than P25, whereas rod-shaped TiO2-NPs were found to be more toxic. Besides, the positively charged particle was slightly more toxic than the negatively charged one. Contrarily, TiO2-NPs, whatever their physicochemical properties, did not induce significant ROS production in both cell systems compared to nontreated control groups. These results may contribute to a better understanding of TiO2-NPs toxicity in relation with their physicochemical features.

关键词： Fourier transform infrared spectroscopy  

摘要： TheN-acetylcysteine (NAC) is a commonly used mucolytic and antioxidant agent. The knowledge of interactions of the NAC with cell membranes is important to understand its mechanism of pharmacological action at the molecular level. To gain a deeper insight into analyzingN-acetylcysteine interactions with multilamellar liposomes of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) in hydrated states at different pH, we performed experimental studies by differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), and Raman spectroscopy. The behavior of the asymmetric stretching band of the PO(2)(-)group was studied by FTIR following the changes that occur in the shape of this band in the pretransition and transition stages from the gel state to the crystalline liquid state. The values of the pretransition temperature (T-p) for different molar ratios of the complex at the two pH values studied were coincident between the measurements by FTIR and DSC, with the results reaffirming the importance of the PO(2)(-)group as a sensor not only in the state of hydration but also in the formation of new intermolecular bonds, which lead to the formation of different domains. The vibrational behavior of the groups of the polar head of the lipid revealed the role of the lipid as an oxidant on the thiol site of the NAC. The results of these studies provide information on membrane integrity and its physicochemical properties. In this aspect, this work has novelty and practicality in pharmacology and analytical chemistry.

关键词： Ionic liquids  

摘要： The physical dissolution of carbohydrates (cellulose, chitin, and starch),i.e., without the formation of covalent bonds requires the solvent to possess certain physicochemical properties. Concentrating on cellulose, the solvent should act both as a Lewis acid and a Lewis base, and disrupt the present hydrophobic interactions, as the biopolymer exhibits amphiphilic characteristics. The quantification of the relative importance of these physicochemical properties helps in predicting the solvent structures, which are expected to be efficient as cellulose solvents. Ionic liquids (ILs) are extensively used as carbohydrate solvents because they disrupt the intramolecular-, intermolecular-, and hydrophobic interactions within the biopolymer structure, leading to its dissolution. Solvatochromic substances (probes) are especially sensitive to one or more of the above-mentioned biopolymer-solvent interactions. Consequently, they are used to predict and rationalize the solvent efficiency. The solvent parameters (descriptors) most widely employed are empirical polarity,E-T(probe), Lewis acidity (SA);Lewis basicity (SB), dipolarity (SD), and polarizability (SP);S refers to the solvent. We synthesized 18 ILs, including derivatives of imidazole, 1,8-diazabicyclo[5.4.0]undec-7-ene, and tetramethylguanidine;the corresponding anions are carboxylates, chloride and dimethylphosphate. We used solvatochromic probes to calculate the descriptors of IL-DMSO (at fixed DMSO mole fraction of 0.6;40 degrees C), and correlatedE(T)(probe) with the other descriptors. We also tested the correlations by using a molar volume of the IL (V-M) instead of SD, and the Lorentz-Lorenz refractive index functionf(n) of the IL-DMSO mixture instead of SP. The quality of the regression analysis increased noticeably when we limited the ILs correlated with those based on imidazole (13 ILs), and used (V-M) andf(n). The regression coefficients showed that SA is the most important descriptor;the solvent empirical pol