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关键词： Tree peony seed protein   Enzymatic hydrolysates   Physicochemical properties   Antioxidant activities  

摘要： The physicochemical and antioxidant properties of tree peony seed protein (TPSP) hydrolysates by Alcalase, Neutrase, Papain, Protamex, and Flavourzyme were investigated in this study. The physicochemical properties were characterized by SDS-PAGE, particle size distribution, fourier transform infrared and fluorescence spectroscopy etc. The antioxidant activities were determined by DPPH radical, ABTS radical, Fe2+ chelating, and reducing power. The results showed five proteases produced hydrolysates with a significantly reduced average particle size, alpha-helices, and surface hydrophobicity compared to TPSP. Alcalase and Neutrase hydrolysis enhanced the nutritional value of the hydrolysates. Alcalase hydrolysates possessed the highest degree of hydrolysis (27.97%) and lowest molecular weight (< 13 kDa) with average particle size (231.33 nm). Alcalase hydrolysate displayed the highest radical scavenging (DPPH IC50 = 0.18 mg/mL, ABTS IC50 = 1.57 mg/mL), Fe2+ chelating activity (IC50 = 0.99 mg/mL), and reducing power (0.594). These results provide the fundamentals for TPSP hydrolysates as antioxidants to be employed in food industry or pharmaceutical industry.

关键词： BciC enzyme   Demethoxycarbonylation   Epimerization   Hydrolysis   Hydroxy group   Stereochemistry  

摘要： Zinc methyl pheophorbides a/a', which possess oxo and methoxycarbonyl groups at the C13(1)- and C13(2)-positions, respectively, on the exo- five membered ring fusing the cyclic tetrapyrrole of their chlorin pi-skeletons, were prepared via chemical modifications of chlorophyll a produced in phototrophs. The C13(1)-hydroxylated and unsubstituted analogues were synthesized by reduction of the ketone moiety. The C13(1)- and C13(2)-stereochemistry of these semi-synthetic compounds was confirmed by H-1 NMR and circular dichroism spectroscopies. A methoxycarbonyl group at the chiral C13(2)-position in the ketone was stereo-inverted under basic conditions, whereas those in the corresponding alcoholic and dihydroforms were not. The in vitro BciC enzymatic reaction of the (13(2)R)-ketone was found to stereoselectively hydrolyze the C13(2)-methoxycarbonyl group, followed by spontaneous decarboxylation. Similarly, the (13(2)R)-COOCH3 group in the (13(1)S)-alcohol was hydrolyzed, whereas the (13(2)R)-COOCH3 group in the (13(1)R)-alcohol was not. After the enzymatic reaction of the C13(1)-dihydro-compound, its (13(2)S)-demethoxycarbonylated and hydroxylated product was observed. (C) 2021 Elsevier Ltd. All rights reserved.

关键词： SDS and CTAB   Vesicles   Ostwald ripening   Physicochemical properties   Thermodynamics   Toxicity  

摘要： It is found that oppositely charged surfactants SDS (sodium dodecyl sulfate) and CTAB (cetyltrimethylammonium bromide) at low concentrations (< critical micelle concentration or CMC) interact, and form self-assemblies (vesicles) in aqueous medium. Physicochemical characterization of the assemblies has been studied and reported. It has been found that the characteristic properties of these assemblies change with time. Investigations on the time dependent changes of such vesicles have been monitored over a period of three months. The properties studied were, turbidity, surface tension, conductance, size and shape, ?-potential, fluorescence anisotropy and quenching of photosensitive dyes in them, thermodynamics of formation as well as toxicity. The surfactants (well below their CMCs) were mixed in different proportions making the final concentration of all at 0.6 mM. They were kept at temperature 303 K, and examined at different times (on the day of mixing, and subsequently after 10, 30, 60, and 90 days). It is known that by the phenomenon of Ostwald Ripening (OR) process, morphological changes in colloidal solution takes place;larger particles grow in size with time at the expense of smaller particles. We studied the OR effect on the physicochemical properties of the growing SDS-CTAB interacted vesicles in aqueous medium. Results and their documentations are herein presented. Such an elaborate study of vesicles with reference to OR process as per our knowledge was not done in the past.

关键词： Ionic liquid   Excess molar volume   Excess isentropic compressibility   Excess sound velocity   Intermolecular free length   Refractive index   Surface tension  

摘要： In this work, the intermolecular interactions for binary mixtures of ionic liquids, 1-butyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium hexafluorophosphate with acetic and propionic acid were evaluated through the measurement of thermophysical properties, density (?), sound velocity (u), refractive index (nD) and surface tension (?) at T = (293.15-333. 15) K and p = 0.1 MPa. The experimental results were used to compute the thermodynamic properties of the binary mixtures, which were then fitted to the Redlich-Kister polynomial equation. The FTIR spectra of the pure components and the binary mixtures at an equimolar composition were recorded to confirm results from thermodynamic properties. The variations of the thermodynamic properties with IL mole fraction and temperature and the effect of the IL anion and alkyl length of the carboxylic acid on the thermodynamic properties have been discussed.

关键词： Redox reactions   Hydrocarbons   Sulfur   Aromatic compounds   Pyrolysis  

摘要： This work assesses the effect of adding CaO during the pyrolysis of waste tires (WT) using a twin-auger reactor on the properties of the pyrolysis derived products. Pyrolysis was conducted in a lab-scale facility at a reactor temperature of 475 degrees C, solid residence time of 3.5 min, WT mass flow rate of 1.16 kg/h, and N-2 flow rate of 300 mL/min. CaO was continuously fed at ratios of 10, 15, and 20 wt %, according to the WT mass flow rate, using two particle size ranges: fine (105-149 mu m) and coarse (149-841 mu m). The resulting tire pyrolysis oil (TPO) was initially characterized in terms of sulfur content, and the sample with the lowest sulfur content, named TPO[CaO], was further studied by different analytical techniques, including GC-MS and H-1 NMR. The tire pyrolysis gas (TPG) and the tire pyrolysis solid (TPS) related to TPO[CaO], so-called TPG[CaO] and TPS[CaO], respectively, were also characterized by gas chromatography, and elemental, proximate, and XRF analyses, respectively. Lastly, an acid demineralization process was carried out to remove some of the inorganic elements in the TPS[CaO]. The addition of 15 wt % of coarse CaO during the pyrolysis of WT resulted in a sulfur reduction in TPO of 26.10%, while viscosity and water content were significantly reduced. The GC-MS analysis revealed a significant presence of benzene, toluene, xylene, and limonene in both TPO and TPO[CaO]. Likewise, H-1 NMR suggested an increase of hydrogen atoms in aromatic, naphthenic, and olefin structures in the TPO[CaO], and a decrease of these atoms in paraffinic structures. Similarly, H-2 and some CxHy compounds increased, while CO2, CO, and H2S decreased in TPG[CaO], which supports the hypothesis of the participation of CaO in several reactions during the pyrolysis of WT. Although the ash content in TPS[CaO] was significantly high after pyrolysis (57.5 wt %), the acid demineralization process was effective at removing 80% of its inorganic content, improving its surface

关键词： Organoclay   CDTEA   smectite   FE-SEM   catalyst carrier  

摘要： This study used the soil representative of Taitung in Taiwan, Santai (St) series soil, as the catalyst carrier and exchanged arboxydecyltriethylammonium chloride (CDTEA) onto it through ion exchange, forming nano-level St-CDTEA organoclay via surface modification and high-temperature sintering. The physical and chemical properties of the St-CDTEA organoclay were then studied via a series of physical and chemical experiments. First, an analysis of the basic properties of St series soil shows that it does not have a high organic matter content because it is affected by either rainfall erosion or intensive farming, which causes a decrease in organic matter after it is consumed or lost. The Fourier-transform infrared spectroscopy (FT-IR) analysis suggests that compared with the unmodified St series soil, C-H bonds are found between 2900 cm-1 and 2850 cm-1 and COOH bond around 1750 cm-1 in St-CDTEA organoclay. A field emission scanning electron microscope (FE-SEM) analysis shows the formation of a crystal structure on the surface of the St-CDTEA organoclay because St series soil contains a larger amount of smectite and the structure of the St-CDTEA organoclay absorbs a significant amount of CDTEA molecules (the molecular structure of CDTEA contains three ethyls) after high-temperature sintering.

关键词： Linoleic acid  

摘要： Pomegranate seeds (Punica granatum L.) are quantitatively and qualitatively a relevant agri-food by-product which is rich in molecules beneficial to human health. In order to valorize this resource, this study aims to evaluate and to compare, for the first time, the characteristics of fruit seeds and seed oils of ten pomegranate cultivars grown in the Center of Morocco. Physical and biometric parameters of seeds, fatty acid composition, physicochemical criteria, and antioxidant activity of seed oils were determined. The results showed significant differences between the ten studied cultivars. The seeds yielded oil contents ranging from 17.59% to 24.69% and presented high contents of polyunsaturated fatty acids (PUFAs) exceeding 89%. The major fatty acid was punicic acid, which represented more than 80% of fatty acids, while other fatty acids such as linoleic acid, oleic acid, and palmitic acid could be considered a minority. Oils showed yellow colour due to the contents of chlorophyll (0.12-1.87 mg/kg) and pheophytin (0.39-3.87 mg/kg) and presented high antioxidant activity (IC50: 0.69-1.80 mg/mL). Therefore, the studied pomegranate seeds had a very good oil yield, and these oils have presented an optimal fatty acid composition and high levels of antioxidant activity. Thus, they could be useful in the formulation of novel foods or used as preservatives and functional components in food industry.

关键词： Redox reactions   Oxides   Anions   Oxidation state   Metal clusters   Cluster chemistry  

摘要： Here, we report our findings related to the structural and electronic considerations that influence the rate of oxygen-atom transfer (OAT) to oxygen-deficient polyoxovanadate alkoxide (POV-alkoxide) clusters ([V6O6(OC2H5)(12)](n);n = 1-, 0, 1+). A comparison of the reaction times required for the reduction of nitrogen-containing oxyanions (NOx-, x = 2, 3) by the POV-ethoxide cluster in its anionic (1-V6O61-;(VV5IV)-V-III), neutral (4-V6O60;(VVV4VV)-V-III-V-I), or cationic (6-V6O61+;(VV3V2V)-V-III-V-IV) charge state reveals that OAT is significantly influenced by three factors: (1) ion-pairing interactions between the POV-alkoxide and the negatively charged oxyanion;(2) oxidation states of remote vanadyl ions in the Lindqvist assembly;(3) the steric bulk surrounding the coordinatively unsaturated VIII ion. This work provides atomic-level insight related to structure-function relationships that govern the rate of OAT at metal oxide surfaces using polyoxometalate clusters as molecular models.

关键词： Sludge conditioning and dewatering   Thermal-acidic-modified kaolin   Waste activated sludge   Physical-chemical conditioner  

摘要： In this study, the effect of thermal-acidic-modified kaolin (TAMK) on waste activated sludge (WAS) conditioning and dewatering was investigated for the first time. Using analyses of XRD, XRF, FT-IR, porosity and specific surface area, structural changes of kaolin were evaluated before and after modification. Conditioning with TAMK reduced the specific resistance to filterability (SRF) and time to filter (TTF), capillary suction time (CST) of WAS to 91.2%, 73.1% and 70.8% respectively. WAS conditioning with TAMK resulted in reducing compressibility and increasing filtration yield, the porosity of WAS, that indicating its function as a physical conditioner (skeleton builder). TAMK increased the WAS particle size significantly (from 47.8 ?m to 451 ?m) and improved their resistance against shear force. TAMK decreased the bound water (58.1%), negative zeta potential (from -31.4 mV to -7.2 mV) and EPS (extracellular polymeric substances) of WAS, indicating its function as a chemical conditioner. This study showed that TAMK acts as a physical-chemical conditioner. Also, the estimated costs of WAS conditioning with TAMK is 35.22 $/ton dry solids (DS). In general, TAMK is an affordable, inexpensive and effective option for sludge conditioning and dewatering.

关键词： Diesel engine   Soot particle   Early injection   Nanostructure   Oxidation reactivity  

摘要： The early injection is widely employed in advanced combustion technologies, which could substantially impact the engine particulate matter (PM) emissions. The primary objective of the present study was to investigate the effect of early injection on the diesel soot particle characteristics, so as to obtain comprehensive information when using a diesel particulate filter (DPF) for PM reduction. Three operating modes were employed, including P (-50 CA), P (-30 CA) and P (-10 CA), which were marked by the early injection timing. The main injection was adjusted such that three modes have similar combustion phases. The soot particles were produced from a heavyduty diesel engine. Transmission electron microscopy (TEM) and Raman spectroscopy were used to analyze morphology, nanostructure and graphitization degree. Thermalgravimetric analysis (TGA) was done to quantify the volatile fraction content of particles, as well as the oxidation reactivity. Results showed that with early injection advanced, primary particle size became bigger with more disordered nanostructure and lower graphitization degree. Meanwhile, the advanced early injection resulted in relatively more organic carbon (OC) and higher oxidation reactivity of the produced soot particles because incomplete combustion caused by spray-wall impingement and suppressed in-cylinder PM oxidation process.