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关键词： Polyelectrolytes   Complexes   Adsorption   Solid surfaces   Coating   Solution characterization   Overlapping concentration  

摘要： The adsorption of mixtures of charged polymers onto solid surfaces presents a big interest in different techno-logical and industrial fields, and in particular, in cosmetics. This requires to deepen on the most fundamental physico-chemical bases governing the deposition, which is generally correlated to the interactions occurring in solution. This work explores the interaction in solution of model polymer mixtures formed by a cationic ho-mopolymer (poly (diallyl-dimethyl-ammonium chloride), PDADMAC) and a zwitterionic copolymer (copolymer of acrylic acid, 3-Trimethylammonium propyl methacrylamide chloride and acrylamide, Merquat 2003), and the adsorption of such mixtures onto negatively charged surfaces. The analysis of the interactions occurring in so-lution between both polymers performed using dynamic light scattering (DLS), electrophoretic mobility and viscosity measurements, combined with the study of the deposition of the layers of mixtures containing different weight fractions of each polymer using ellipsometry and quartz crystal microbalance with dissipation monitoring (QCM-D) has shown that the interpolymer complexes formed in solution, and their composition, governs the deposition onto the solid surface and the tribological properties of the adsorbed layers as shown the Surface Force Apparatus (SFA) experiments, allowing for a control of the physico-chemical properties and structure of the layers. Furthermore, the use of Self Consistent Mean Fields Calculations (SCF) confirms the picture obtained from the experimental studies of the adsorbed layers, providing a prediction of the distribution of the polymer chains within the adsorbed layers. It is expected that this study can help on the understanding of the correlations existing between the behavior of future associations of innovative and eco-sustainable polymers and their adsorption processes onto solid surface.

关键词： Chalcone   Pyrazoline   Stokes shift   Surfactants   CMC  

摘要： The new extended pi-bond pyrazoline derivative (ENTD) was prepared from heterocyclic chalcone with 2-hydrazinylbenzo[d] thiazole. The spectroscopic methods established the structure of the ENTD, and the elemental analysis established the purity of the ENTD. In ten different solvents, physicochemical ENTD parameters such as the molar absorption coefficient, transition dipole moments, Stokes shift, oscillator intensity and fluorescence quantum yield were determined to see the effect of the solvent with pyrazoline derivative (ENTD) on the basis of different polarity. In addition, the interaction of ENTD chromophore with the cationic and anionic surfactants have been studied. The intensity of fluorescence spectrum of the ENTD was found to increase with an increase in the surfactant concentration. This indicates that there is a strong interaction between ENTD and surfactants. The ENTD chromophore can therefore be used as a probe to define the surfactants' CMC. (C) 2020 Published by Elsevier B.V.

关键词： Density   speed of sound   excess molar volume   FT-IR spectrum  

摘要： Densities (rho) and speed of sound (u) data for anisole with o-cresol, m-cresol and p-cresol binary liquid mixtures were estimated over the temperature at T = (303.15, 308.15 and 313.15) K and at atmospheric pressure. The experimental data were used to compute excess volume (V-E) and excess isentropic compressibilities (kappa(E)(S)) at all the investigated temperatures. The magnitude of excess properties is negative for all the mixtures containing anisole with isomeric cresols due to existence of solvent-solute interactions of hydrogen bond. The V-E and kappa(E)(S) were fitted and correlated with Redlich-Kister type equation. Further, the measured sound speed data were compared with Schaff's Collision Factor Theory (CFT) and Jacobson's Free length Theory (FLT) to check their predictive capability. The resultant of these properties, with structure and temperature, was explained in terms of molecular interactions owing to physiochemical effects between the unlike molecules of the binary mixtures. Further, FT-IR data were also collected to confirm the existence of hydrogen bonding between molecules.

关键词： Celosia argentea flower fiber   FTIR   XRD   TGA   AFM   SEM  

摘要： This study was aimed at understanding the characteristics of Celosia argentea fiber (CAF) and its physicochemical properties. The physicochemical properties of CAF were analyzed by FT-IR, XRD, TGA, SEM, and AFM analysis. Cellulose content (64.34wt.%), density (843 kg/m(3)) and crystallinity index (52.54%) properties were identified in the CAF while the thermal studies performed by TG and DTG technique revealed that the maximum degradation temperature is 324 degrees C with a kinetic activation energy of 61.393 kJ/mol. From the results, it is evident that the CAF could be one of the future reinforcement materials for green composites applications.

关键词： nanoliposome   organogel   vitamin D-3   encapsulation   EPR   DLS   zeta potential  

摘要： The inherent thermodynamic instability of liposomes during production and storage has limited their widespread applications. Therefore, a novel structure of food-grade nanoliposomes stabilized by a 3D organogel network within the bilayer shell was developed through the extrusion process and successfully applied to encapsulate vitamin D-3. A huge flocculation and a significant reduction of zeta potential (-17 mV) were observed in control nanoliposomes (without the organogel shell) after 2 months of storage at 4 degrees C, while the sample with a gelled bilayer showed excellent stability with a particle diameter of 105 nm and a high negative zeta potential (-63.4 mV), even after 3 months. The development of spherical vesicles was confirmed by TEM. Interestingly, the gelled bilayer shell led to improved stability against osmotically active divalent salt ions. Electron paramagnetic resonance confirmed the higher rigidity of the shell bilayer upon gelation. The novel liposome offered a dramatic increase in encapsulation efficiency and loading of vitamin D-3 compared to those of control.

关键词： Physicochemical properties  

摘要： Unscientific application of fecal sludge (FS) on agricultural fields in India has led to fecal coliform and heavy metal accumulation in the food chain. The design of FS treatment depends on accurate knowledge of its characteristics, which is seldom available for nonurban India, where most of the agriculture sector is concentrated. In this study, nonurban FS from India has been systematically characterized for physicochemical properties, nutrient, and pathogenic content to assess its ability to be used as a fertilizer. It was found that the collected FS has nutrients (nitrogen = 3.0% +/- 0.4%, phosphorus = 29.07 +/- 4.48 mg/L, potassium = 43.57 +/- 0.74 mg/L), organic carbon (33% +/- 3.2%), and physicochemical properties that qualify the Indian specifications of organic fertilizers, whereas its pathogenic content (i.e., 6 log cfu/g, and 6 to 13 viable helminth ova/g) is high as per US regulations. Thus, collected FS requires treatment by unplanted drying bed and co-composting to be used as fertilizer. (C) 2021 American Society of Civil Engineers.

关键词： Aquatic vegetable   Starch   Morphology   Pasting property   Thermal property  

摘要： Nelumbo nucifera Gaertn., Eleocharis dulcis, Sagiaaria sagittifolia L., and Trapa bispinosa Roxb. are common aquatic vegetables that are rich in starch. Starches from these four aquatic vegetables and their applications in edible films were studied to facilitate full use of starch resources. Significant differences in transparency, freeze-thaw stability, water solubility index, swelling power, water and oil absorption capacities, starch particle morphology, and rheology were observed among the starches from these four aquatic vegetables. All starches exhibited a typical "A" type diffraction pattern. N. nucifera, E. dulcis, and S. sagiatfolia starches have similar thermal properties, while T. bispinosa starch has a higher gelatinization temperature. S. sagittifolia starch film has the highest transparency and lower WVP and water solubility. These results will promote the development of products based on starch obtained from aquatic vegetables. (C) 2021 Elsevier B.V. All rights reserved.

关键词： Ignition   Coal combustion   Oxy-fuel   Heterogeneous and homogeneous ignition   Physicochemical property  

摘要： Coal combustion is a complex phenomenon involving multiscale chemical and physical processes. In this paper, the physical and chemical effects of CO2 on the ignition behaviors of dispersed coal particles are investigated based on a self-developed transient ignition model. Attention has been paid on the separate effects of CO2, namely the thermal conductivity, the species diffusion rate, the heat capacity, and the gasification reaction, on the ignition behaviors in oxy-fuel ambience. Differences of coal ignition delay time and ignition modes in air and oxy-fuel ambience are compared. The heterogeneous ignition (HI) is significantly delayed in CO2 ambience, with the most significant contribution from the lower thermal conductivity of CO2. The negative effects of slower species diffusion rates and the endothermic C-CO2 gasification reaction in CO2 are less important;however, they both become prominent with increasing ambient temperature up to 1800 K. By contrast, the gas phase homogeneous ignition (GI) is less sensitive to CO2 enrichment. The positive effects of slower species diffusion rates, together with the negligible effects of higher heat capacity and extra gasification reaction, impair the negative effect from lower thermal conductivity. In summary, the CO2 substitution makes the ignition mode move from the hetero-homogeneous joint regime towards the homogeneous dominant regime. Thus, coal particle ignition under high temperature (1500-1800 K) and low oxygen fraction (similar to 0.1) transits to the homogeneous dominant case, yielding a reduced difference of ignition delay between air and oxy-fuel combustion. This feature has been observed for coal samples of different ranks from several independent macroscopic experiments, and can be well interpreted by the transition mechanism of ignition mode.

关键词： 微课   物理化学   中药学   教学模式  

摘要： 微课作为信息化技术与教育深度融合的重要教学方式之一,以其内容紧凑饱满、逻辑清晰严密、学习方便快捷的优点,得到了高校工作者的广泛关注。本文基于中药学专业物理化学教学过程中普遍存在的“教师难教、学生难学”现象,在探讨中药学专业物理化学教学中存在问题的基础上,将微课与中药学专业物理化学传统教学模式有机结合,突破传统教学模式壁垒,为提升教学效果提供参考。