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关键词： Materials Science   general   Characterization and Evaluation of Materials   Polymer Sciences   Solid Mechanics   Crystallography and Scattering Methods   Classical Mechanics  

摘要： One of the major challenges in off-shore tidal and wave energy devices is the ageing of these structures in the hostile marine environment, which limits their operating life. In this research, mechanical properties of aged glass/epoxy and carbon/epoxy composite specimens including tensile strength, Young's modulus, flexural strength, and shear strength, following immersion in a representative accelerated marine degradation environment (artificial seawater, with 3.5% salinity at room temperature and 60 degrees C) have been investigated. The microstructure and physicochemical characterization of the aged samples were assessed via microscopic imaging, micro-CT scanning and differential scanning calorimetry. The degradation phenomenon was apparent in the change of mechanical properties and microstructure of composite laminates (micro-cracks and debonding between matrix and fibre). Generally, the ageing process had a more severe effect on tensile and shear strengths of glass/epoxy samples than those of carbon/epoxy specimens. Reversely, the results of bending tests of carbon/epoxy composites showed more drop-in flexural properties than glass/epoxy samples. The results revealed that degradation mechanisms continue even after reaching the saturation point in composite materials. The achievements of this research present a good understanding of the effect of degradation of composite materials in salt water to deal with their application in real service environment.

关键词： 物理化学   化学实验  

ISBN: (纸本)9787305254369

摘要： 本书由南京大学化学系物理化学教研室同仁们，依据长期物化实验教学研究与实践的成果编写而成，内容分绪论、实验、基础知识与技术、附录四部分。实验部分主要包括热力学、动力学、电化学、表面性质与胶体化学、结构化学共29个实验项目，在内容上力争让有余力的学生选做部分实验。仪器设备上，尽量采用国内先进的仪器和直观性强的自制仪器，使学生迅速了解与掌握先进的实验技术。

关键词： Ca-bentonite   Calcination   High temperature   Opal-CT   Mesoporous   Mullite  

摘要： Three Ca-bentonite samples from unye (NE Turkey) were calcined up to 1000 degrees C with 200 degrees C increments at 25 min. The physico-chemical and mineralogical effects of high-temperature loadings were evaluated by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), Brunauer-Emmett-Teller (BET) and loss on ignition (LOI) analysis. The results of the experiments show that the dehydration up to 400 degrees C does not alter the properties of Ca-bentonites significantly;however, the endothermic reactions due to dehydroxylation between 400 and 800 degrees C cause the deformation in the Ca-smectite crystal structure revealed by the collapse of the basal reflection from 1.4 to 1.0 nm and the gradual disappearance of OH stretching of structural hydroxyl groups and decrease in specific surface area and the closure of micropores. By calcination at 1000 degrees C, the specific surface area reaches the minima of 1.33-2.05 m(2) g(-1) for all the samples, and the structure of Ca-smectite is almost completely decomposed for CaB2 and CaB3, however, partially decomposed for CaB1 due to incomplete dehydroxylation stage. The crystallinity of opal-CT intensifies, and the formation of amorphous silica phases is promoted for all samples at 1000 degrees C;however, the formation of mullite is enhanced only for CaB2 and CaB3. The sintering effect is revealed as much larger aggregates with more rounded morphologies. It is also determined that the calcination up to 1000 degrees C does not affect the mesoporous characteristics of Ca-bentonite samples.

关键词： Sour lemon peel powder   Xanthan gum   TiO2-Ag Nanoparticles   Agricultural waste  

摘要： The aim of this study was to prepare a biodegradable film of sour lemon peel waste. The film of lemon peel powder (LPP) was modified with xanthan gum (XG) and TiO2-Ag nanoparticles (LPP/XG/TiO2-Ag). For this purpose, a central composite design was used to investigate the effect of xanthan gum and TiO2-Ag nanoparticles on the physicochemical and structural properties of the produced film. The results showed that the addition of xanthan gum led to an increase in thickness, moisture and index a of the samples and on the other hand a decrease in moisture and index a was observed with the addition of TiO2-Ag. With increasing xanthan gum, index b decreased slightly and with increasing TiO2-Ag, the amount of yellowness increased. With the addition of gum and nanoparticles, the antioxidant properties were slightly increased. With the addition of xanthan gum and TiO2-Ag, tensile strength and Young's modulus of the film significantly increased and the solubility and WVP decreased (P < 0.05). The FT-IR results showed the electrostatic interaction between lemon peel powder, TiO2-Ag and gum. In the SEM images, films containing TiO2-Ag and gum showed a homogeneous film with a granular state. According to the TGA results, the film samples containing gum and TiO2-Ag had better thermal stability than the control sample. The XRD results showed that adding TiO2-Ag and XG to the films reduced crystalline properties of film. Also, the results of antimicrobial activity against E. coli and Staphylococcus aureus showed that XG and TiO2-Ag increased antibacterial activity of film.

关键词： aluminum powder   modification   vanadium pentoxide   phase analysis   morphology   microstructure   composites  

摘要： The phase composition and morphology of a synthesized material based on aluminum powder modified with various concentrations of V2O5 (3, 5, 10 wt %)-compacted in the form of tablets and sintered at temperatures of 820 and 900 degrees C in He and air-have been studied by X-ray analysis and electron microscopy. It is shown that the phase components are uniformly distributed in the plane of the microsection, and their ratio is determined by the temperature and time of annealing of the pellets. It has been established that, due to the activation of processes on the surface of modified particles of aluminum powder, it becomes possible to control the properties of interphase boundaries in oxidizing and inert media.

关键词： Lignin recalcitrance   Delignification   Saccharification   Lignin recovery   Lignin applications  

摘要： Effective pretreatment of lignocellulosic biomass (LCB) is one of the most important steps in biorefinery, ensuring the quality and commercial viability of the overall biopmcess. Lignin recalcitrance in LCB is a major bottleneck in biological conversion as the polymerization of lignin with hemicellulose hinders enzyme accessibility and further bioconversion to fuels and chemicals. Therefore, there is a need to delignify LCB to ease further bioprocessing. The efficiency of delignification, quality and quantity of the desired products, and generation of inhibitors depend upon the type of pretreatment employed. This review summarizes different single and integrated physicochemical pretreatments for delignification. Additionally, conditions required for effective delignification and the advantages and drawbacks of each method were evaluated. Advances in overcoming the recalcitrance of residual lignin to saccharification and the methods to recover lignin after delignification are also discussed. Efficient lignin recovery and valorization strategies provide an avenue for the sustainable lignocellulose biorefinery.

关键词： Anthocyanins  

摘要： In this study, some physicochemical and bioactive properties of Rosa damascena Mill. and the effect of different extraction methods and conditions on total monomeric anthocyanin (TMA) extraction were investigated. The average petal weights, petal areas, L*, a*, and b* values, dry matter, pH, titration acidity, L-ascorbic acid, TMA, and total phenolic content of the samples were 2.49 g, 6.04 cm(2), 54.01, 37.30, 22.72, 18.65%, 5.45, 0.11 mg/100 g, 1,366.52 mg/kg DW, 515.79 mg C3G Eq./100 g DM and 4,353.52 mg GAE/100 g DM, respectively. Catechin, ellagic acid, rutin, gallic acid, and two different anthocyanins were detected. The mass transfer coefficient values in conventional (20, 40, and 60 degrees C) and ultrasound-assisted extraction (50%, 75%, and 100% amplitude) were 0.068, 0.324, and 0.922 ml/cm(2) and 2.178, 3.822, and 7.812 ml/cm(2) min, respectively. Results showed that anthocyanins can be extracted faster and with higher yields by ultrasound-assisted extraction. Novelty impact statement Rosa damascena Mill. petals have attractive red color and are rich sources of anthocyanins. Anthocyanins are water-soluble natural pigment and have the positive effects on human health. The anthocyanin extraction, which takes 210 min at 60 degrees C with conventional extraction, can be shortened up to 18 min at 100% ultrasound amplitude by ultrasound-assisted extraction.

关键词： Persian gum   Edible film   Emulsified oil   Glycerol   Modification  

摘要： This work focused on the development and characterization of relatively novel edible films from Persian gum (PG) under different concentrations of glycerol and emulsified oil droplets. At 0.3% of glycerol, PG films were highly brittle for studying their mechanical properties. Higher concentrations of glycerol increased the ductility of films. The increase of oil droplet concentrations resulted in a reduction in the tensile strength, whereas, elongation at break increased. Incorporating the emulsified oil droplets resulted in a significant reduction of water solubility, swelling ability, and water vapor permeability of films. The presence of glycerol and emulsified oil droplets within the film matrix was confirmed by FTIR spectroscopy. SEM micrographs revealed that the plasticized PG films had a uniform microstructure, while, incorporating emulsified oil droplets led to relatively rough microstructure. In conclusion, PG films containing 0.9% glycerol and 1% emulsified oil droplets had desirable properties, which can be exploited for food packaging.

关键词： Starch  

摘要： The physicochemical characteristics in terms of composition, pasting properties, in vitro starch digestibility, morphology, XRD, FT-IR, and functional properties of starch, isolated from the kernels of Euryale ferox seed cultivated in Northeastern Region of India were studied and utilized them in formulation of bread. E. ferox kernel starch (EFKS) exhibited an A-type diffraction pattern and granule sizes ranged from 1 to 3 mu m in diameter and were polyhedral shape. EFKS exhibited high pasting temperature indicating its potential to incorporate in products requiring higher temperature to cook, such as baked items like bread. The effects of replacing refined wheat flour with native EFKS (5%-50% db) on bread quality attributes were investigated, and sensory results suggested that bread with 20% EFKS incorporation was acceptable, but bread with higher concentrations of EFKS produced smaller loaf volumes. Results evidenced that EFKS is a novel starch source and has an immense potential in both food and non-food industries. Novelty impact statement Results of the study have the credential evidence to corroborate that the Euryale ferox kernel starch (EFKS) has strong potential applications in food industries. The study also clearly revealed that EFKS can replace up to 20% of wheat flour for bread making with acceptable sensory attributes. The EFKS is comparable to popularly acceptable commercial starch-like rice and has potential for enormous food and non-food applications and can be a money spinner for entrepreneurs.

关键词： Fortified rice kernels   parboiled rice   raw rice   system parameters   cooking characteristics   textural properties  

摘要： Fortified rice kernels (FRK) are extruded rice-shaped kernels manufactured by blending broken rice flour and vitamin-mineral premix. In this study, four parboiled and three raw rice with intermediate amylose content (20-24%) were processed to manufacture FRK. The system parameters (torque and die pressure), physicochemical properties (length, lightness, water absorption index and water solubility index), cooking properties (cooking time, solid loss, elongation) and textural properties of FRK were analysed and correlated using the Pearson correlation coefficient. The torque and die pressure were 16.76-22.76 Nm and 92.56-136.41 bar, respectively. Compared to raw rice, the parboiled rice showed the highest torque, die pressure and axial expansion in uncooked FRK while longer cooking times, higher elongation ratio and hardness;lesser water absorption ratio and solid loss in cooked FRK. The raw rice FRK showed higher lightness. There was a significant difference between all FRK for water absorption index (1.74-2.52) and water solubility index (2.06-3.53%).