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关键词： Magnetic materials   Electron microscopy   Photoelectron spectroscopy   Magnetic properties   Surface properties  

摘要： Silica-coated iron oxide magnetic nanoparticles to be employed as the starting core for easily-recoverable heterogeneous catalysts supports, were synthesized. We tuned both the properties of the magnetic core and of the covering shell, with particular emphasis on the optimization of the silica layer thickness. Afterwards, structural-sensitive techniques (XRD, BET surface area analysis), surface-sensitive techniques (ATR-IR, XPS), imaging (SEM, TEM), elemental analyses (ICP-MS) and magnetization analyses (AGFM), were employed to unravel the features of the synthesized materials. The oxidation of cis-cyclooctene with tert-butyl hydroperoxide in presence of MNPs was used as probe reaction to check the reactivity of the NPs and the effectiveness of the silica shield. The results of these tests showed its chemical inertia confirming the absence of any detrimental iron oxide catalyzed side-reactions or magnetic core modification.

关键词： Drying  

摘要： In this paper, the effects of electrohydrodynamic drying and different pretreatments such as prefreezing (washing, prefreezing at -20celcius for 24 hr, thawing, slicing, color care, and drying) and precooking (washing, slicing, color care, precooking, and drying) on the physicochemical and functional properties of potato flours were evaluated and compared with a control sample (washing, slicing, color care, and drying), using standard methods. The results revealed that in the early stage of electrohydrodynamic drying, the drying rate of potatoes gradually increased with the increase of voltage. And the oil absorption index and water solubility index of the potato flours prepared by 20-KV drying voltage were greater than other voltages as a whole. Compared with the control group and precooking treatment, the drying time of prefreezing potatoes reduced by 1-2 hr. The characteristics of potato flours prepared by prefreezing treatment were higher than that of the control group and precooking treatment, such as amylose content, water absorption index, swelling power, and viscosity. The study showed that pretreating potato tuber using prefreezing prior to electrohydrodynamic drying gave the best quality potato flour compared to the control sample. Practical applications Precooking is the main pretreatment method for preparing potato flour. After precooking, the potato flour has been partially gelatinized, and the gelatinized potato flour is difficult to meet the processing requirements. Electrodynamic drying is a new type of nonheat treatment drying method, which can avoid the deterioration of the quality of potato dehydrated products caused by high temperature. And the prefreezing treatment has not been applied in the production of potato flour. Electrohydrodynamic drying combined with prefreezing treatment may help to change the functional properties of potato flours and expand the diversity of potato flours. This drying mode will provide a useful reference for the dryi

关键词： cytotoxicity   hydroxyapatite   precipitation   substitution  

摘要： Hydroxyapatite (HAP) forms the main inorganic component of natural bone and hence has been widely use in implant applications. Ionic substitutions in apatite also gains enormous interest during the recent years due to the crucial role played by these elements in the biological process. In this context, the least investigated elements namely lanthanum (La3+) and praseodymium (Pr3+) have been selected as a potential substitutions in apatite. The results from the analytical techniques confirm the phase purity of the HAP and its ability holds the substitutions at its lattice. Morphological analysis unveils the presence of agglomerated spheroids notwithstanding the ion concentration of substituents. EDX spectra affirm the presence of La and Pr alongside the determined Ca/P atomic ratio of 1.67. La(3+)and Pr(3+)presence envisaged the good antibacterial efficiency against the tested microbes and further demonstrated the biocompatibility nature from the cytotoxicity analysis.

关键词： Thermally exfoliated graphene oxide   Gaseous environment   Physicochemical properties   hydrogen storage  

摘要： The present study compared the effect of different gaseous environments on physicochemical properties and subsequent hydrogen storage ability of thermally exfoliated graphene oxide (EGO). The reducing, inert or oxidizing environments were generated using hydrogen, argon or air as the carrier gas, respectively. The structure of thermally exfoliated graphene oxide depended on the type of gaseous environment. The EGO prepared in presence of Air showed the fluffiest layered structure having highest surface area. The surface area order was EGO(Air) (268 m(2)/g) > EGO(H-2) (248 m(2)/g) > EGO(Ar) (155 m(2)/g). The average pore sizes of EGO(Air) and EGO(H-2) were 2.9 and 2.8 nm, with pore volumes of 1.2 and 1.6 cm(3)/g, respectively. The average pore size for EGO(Ar) was highest at 4.1 nm, associated with presence of larger void space and lowest total pore volume of 1.0 cm(3)/g. Thus, presence of oxidative or reducing atmosphere seemed to be more conducive to exfoliation of layers by gradual removal of functional groups. The inert atmosphere of argon caused severe thermal separation of layers and functional groups, adversely affecting the layered structure as observed. The EGO(Air) also showed highest O/C ratio suggesting presence of significant amount of oxygen-containing functional groups on the surface. The hydrogen uptake order at 77 K and 30 bar was: EGO (Air) 3.34 wt.% > EGO (H-2) 3.12 wt.% > EGO (Ar) 2.2 wt.%. The highest uptake of EGO(Air) might have resulted from highest surface area, highest O/C ratio and presence of considerable pore volume.

关键词： Gradient consistency test   Amino acid properties   Amino acid usage   Protein evolution  

摘要： Proteins can evolve by accumulating changes on amino acid sequences. These changes are mainly caused by missense mutations on its DNA coding sequences. Mutations with neutral or positive effects on fitness can be maintained while deleterious mutations tend to be eliminated by natural selection. Amino acid changes are influenced by the biophysical, chemical, and biological properties of amino acids. There is a multiplicity of amino acid properties that can influence the function and expression of proteins. Amino acid properties can be expressed into numerical indexes, which can help to predict functional and structural aspects of proteins and allow statistical inferences of selection pressure on amino acid usage. The accuracy of these analyses may be compromised by the existence of several numerical indexes that measure the same amino acid property, and the lack of objective parameters to determine the most accurate and biologically relevant index. In the present study, the gradient consistency test was used in order to estimate the magnitude of directional selection imparted by amino acid biochemical and biophysical properties on protein evolution.

关键词： Kinetics   Browning index   Sugars   beta-cryptoxanthin   beta-carotene   Lycopene  

摘要： Vacuum frying is an alternative technology to obtain fruit snacks with higher sensory and nutritional quality compared to traditional fried snacks. Vacuum frying of a carotenoid-rich fruit (red-fleshed papaya) was performed at 25 kPa, using soybean oil at 100, 120, and 140 degrees C from 0 to 14 min. The study aimed to monitor and model physicochemical changes that chips undergo during vacuum frying, which are related to their sensory and nutritional attributes. Moisture content, a(w), oil uptake, sugar content, browning index (BI) and carotenoid contents were monitored. Water loss and oil uptake followed first-order kinetics while the decrease in a(w) followed a logistic trend. Glucose and fructose followed the same degradation pattern while BI and sucrose content increased as a function of frying time and oil temperature. beta-cryptoxanthin (BCX) loss followed second-order kinetics and retention was 60 and 40% after 14 min at 120 and 140 degrees C, respectively. Contents of lycopene and beta-carotene were increased suggesting an improvement in availability of these compounds to extraction. Optimal vacuum frying conditions for processing papaya fruit comprise a combination of temperatures (107-120 degrees C) and frying times (9-14 min) to produce quality papaya chips with a(w) ranging from 0.1 to 0.3, low color degradation and BCX loss <= 30%.

关键词： Citrus peel   Phenolic compounds   Carotenoids   Saccharomyces yeast   Non-saccharomyces yeast  

摘要： The present study aimed to investigate the effects of alcoholic fermentation on the physicochemical and phytochemical characteristics of the tissues flavedo and albedo from five citrus fruits, namely grapefruit (Citrus paradisi), lemon (Citrus limon), and sweet oranges (Citrus sinensis) cvs. 'Tarocco', 'Washington navel', and 'Moro'. The tissues were fermented with pure and mixed cultures of Saccharomyces cerevisiae, Brettanomyces bruxellensis, and Torulaspora delbrueckii. Flavedo and albedo increased the water holding capacity (WHC) and oil binding capacity (OBC) when subjected to fermentation. The treatment with B. bruxellensis resulted the most effective at enhancing WHC and OBC, e.g., lemon flavedo achieved the highest WHC (9.67 +/- 0.15 g/g;P < 0.001). Concerning the phytochemicals, samples increased the total contents of phenolic compounds and carotenoids upon fermentation. The orange 'Tarocco' benefited markedly as regards phenolic compounds, e.g., the naringenin and hesperidin contents reached 244 +/- 15.5 and 2900 +/- 160 mg kg(-1) DW, respectively, when the albedo was fermented with T. delbrueckii, with increases above 4-folds. Likewise, the total carotenoids were augmented (P < 0.001) when flavedo samples were treated with T. delbrueckii. Overall, the performed alcoholic fermentations ameliorated the physicochemical and phytochemical characteristics of the selected citrus tissues, and are recommended to expand their utilization in the nutraceutical sector.

关键词： 物理化学-化学实验  

ISBN: (纸本)9787030686251

摘要： 本书是在《物理化学实验》（科学出版社，2008年，袁誉洪）的基础上修订而成，基本保持了第一版的特色，并对原有实验进行了必要筛选和精炼，对少数实验进行类别调整，新增了部分内容等等。

关键词： Textures  

摘要： Barramundi (Lates calcarifer) muscle with brine 2% in Stand-up-retort pouches was treated at different temperatures from 90 degrees C to 120 degrees C at 600 MPa, 5 min. Samples retorted with F-o = 3.38 min were used as control. Texture attributes such as hardness and springiness of the high pressure thermal sterilized (HPTS) barramundi samples were increased compared to the retorted samples. Color, TBA, and pH values were similar for all treatments, except for a significant increase in pH of samples treated at 90 degrees C, 600 MPa, 5 min after 3 months of storage, indicating microbial spoilage. Textural sensory quality of HPTS products was also better than retorted products. High pressure thermal sterilization (HPTS) at 600 MPa and 110 degrees C or 120 degrees C for 5 min resulted in shelf-stable barramundi products. Overall, HTPS could be a feasible option for the production of sterilized fish product with better texture compared to conventional retorted fish product. Practical applications High pressure and thermal sterilization (HPTS) of food products is emerging as an innovative method with many advantages. HPTS could result in better nutrition and sensory quality of sterilized food products as lower thermal load applied to the product and less unwanted food processing contaminants such as furan are also produced in food products. However, the application of HPTS on food products, especially, seafood products is still in early stage and limited. The result of this study could be used to develop a scale-up process for sterilized barramundi products in the food industry.

关键词： Mango kernel   Starch   Deep-fried   Extruded   In vitro digestibility  

摘要： The waste produced by the food industry causes serious environmental problems, such as impacts on climate change, food safety, and economic losses. Because of the economic importance of mango, the main byproducts, namely, the peel and the seed, are discarded as agro-industrial waste. The aim of the study was to produce extruded mango kernels to evaluate the physicochemical, microstructural and in vitro starch digestibility characteristics of deep fried to gain information on the possible use of mango kernel flour for food and nonfood purposes. Flour of mango kernel was prepared, and moisture content was adjusted to extrusion. The extruded material was deep-fried and studied in terms of chemical composition, microstructure, gelatinization patterns and in vitro starch hydrolysis. The microstructure results showed that the presence of oil in the food matrix helped change the starch structure in deep-fried extrusion due to amylose-lipid interactions. The deep-fried process reduced the in vitro hydrolysis rate when compared with the extruded matrix. Mango byproducts, especially seeds (kernels), are considered cheaper sources of valuable food and nutraceutical ingredients.