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191.
192.
The photoelectrochemical performance of a BiVO4 photoanode is limited by its poor charge transport properties, despite other useful optical absorption properties. Modifying the surface charge transport properties by forming heterojunction of BiVO4 with other metal oxides layers having ultralow thickness is a promising route, as it may facilitate charge separation/transport without affecting other properties of BiVO4. In this study, the structural, optical and PEC properties of heterojunction of BiVO4 having ultrathin overlayers of Fe2O3, MoO3 and ZnO has been investigated. The electrochemical impedance (via electrochemical impedance spectra in PEC cell) and surface photovoltage (using KPFM) measurements indicates improved charge transport owing to staggered band alignment and favourable band bending in case of BiVO4/MoO3 heterojunction as compared to pristine BiVO4, BiVO4/Fe2O3 and BiVO4/ZnO heterojunctions. Enhanced photocurrent density in BiVO4/MoO3 of ~0.22 mA/cm2 at 1.23 VRHE which is 6 times as compared to pristine BiVO4 layers has been observed. The results of the present study show that by forming heterojunction with a suitable semiconductor material can be used to enhance the PEC response by modifying the surface charge transfer characteristics and there is a large possibility of using other semiconductor materials for further investigations and improvement. 相似文献
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195.
Nancy John Nisha J. Tharayil Malu Somaraj 《Journal of Materials Science: Materials in Electronics》2017,28(8):5860-5865
Tin oxide nanoparticles (size?=?14 nm) have been prepared using DNA, a biological molecule, by co-precipitation method. The SnO2 catalysts were characterized by X-ray diffraction, scanning electron microscope, transmission electron spectroscopy, fourier transform infra-red spectroscopy, photoluminescence spectroscopy and UV–Vis spectroscopy. The photocatalytic properties of SnO2 nanoparticles were investigated via methyl orange as a model organic compound under UV light irradiation. The study proves SnO2 as an efficient catalyst in removing organic pollutants in water. 相似文献
196.
Nisha P Bineesh Rekha S Singhal Aniruddha B Pandit 《Journal of the science of food and agriculture》2005,85(11):1953-1958
The kinetics of ascorbic acid degradation in drumstick (Moringa olifera) leaves as well as in pure ascorbic acid solutions at the initial concentrations present in drumstick leaves over a temperature range of 50–120 °C (isothermal temperature process) has been studied. The degradation kinetics of ascorbic acid was also evaluated in normal open‐pan cooking, pressure‐cooking and a newly developed and patented fuel‐efficient eco cooker (non‐isothermal heating process). The ascorbic acid degradation followed first‐order reaction kinetics where the rate constant increased with an increase in the temperature. The temperature dependence of degradation was adequately modelled by the Arrhenius equation. A mathematical model was developed using the isothermal kinetic parameters obtained to predict the losses of ascorbic acid from the time–temperature data of the non‐isothermal heating/processing method. The results obtained indicate the ascorbic acid degradation is of similar order of magnitude in all the methods of cooking. Copyright © 2005 Society of Chemical Industry 相似文献
197.
Bushra Sultana Farooq Anwar & Shahid Iqbal 《International Journal of Food Science & Technology》2008,43(3):560-567
The effects of different cooking methods (boiling, frying and microwave cooking) on the antioxidant activity of some selected vegetables (peas, carrot, spinach, cabbage, cauliflower, yellow turnip and white turnip) were assessed by measuring the total phenolic contents (TPC), reducing power and percentage inhibition in linoleic acid system. TPC (gallic acid equivalents g/100 g of dry weight) and reducing power of the methanolic extracts of raw‐, microwaved‐, boiled‐ and fried vegetables ranged 0.333–2.97, 0.52–2.68, 0.48–2.08, 1.00–2.02 and 0.391–2.24, 0.822–1.10, 0.547–1.16, 0.910–4.07, respectively. The level of inhibition of peroxidation ranged 71.4–89.0, 66.4–87.3, 73.2–89.2 and 77.4–91.3%, respectively. Antioxidant activity of the vegetables examined was appreciably affected because of varying cooking treatments. TPC of vegetables, generally, decreased by boiling, frying and microwave cooking. There was a significant (P < 0.05) increase in reducing power as a result of frying. However, boiling and microwave cooking did not affect reducing power. Inhibition of peroxidation increased by boiling and frying, whereas, in contrast it was decreased by microwave cooking. The results of the present investigation showed that all the cooking methods affected the antioxidant properties of the vegetables; however, microwave treatment exhibited more deleterious effects when compared with those of other treatments. Thus an appropriate method might be sought for the processing of such vegetables to retain their antioxidant components at maximum level. 相似文献
198.
Adenanthera pavonina L. is indigenous to Pakistan a proximate analysis of the seeds was carried out and a physicochemical characterization of the seed oil and also a quality evaluation of the oil was made. The hexane-extracted oil content of the seed was 13.32 ± 0.55 %. Analysis showed the seed of A. pavonina contained appreciable amounts of protein (22.14 ± 0.78 %). Fiber and ash contents were 3.13 ± 0.64 and 4.53 ± 0.47 %, respectively. Triacylglycerol (97.51 ± 1.12 %) was predominantly present in the seed oil. Unsaponifiable matter (0.95 ± 0.10 %), peroxide value (11.43 ± 0.51 mequiv./kg) and saponification value (196.3 ± 0.87 mg of KOH/g of oil), iodine value (83.73 ± 1.18 g I/100 g oil) are in close agreement with the edible seed oils. α-Tocopherol was the predominant tocopherol 152.33 ± 13.19 mg/kg of oil while sterols are present at a significant level. Linoleic acid (42.97 ± 0.91 %) and oleic acid (17.89 ± 0.54 %) were found predominantly in unsaturated fatty acids while lignoceric acid (20.24 ± 1.12 %) was the predominant one among the saturated fatty acids. Lignoceric acid is rarely found in seed which is an essential nutrient for growth, development and maintenance of the brain. It is concluded that A. pavonina seeds appear to be a potential source of lignoceric acid and linoleic acid. This oil can be utilized in the manufacture of cosmetics, paints, varnishes, soaps, pharmaceutical products, biodiesel and blended formulations. The high protein content revealed that the seeds could be a good source of energy. 相似文献
199.
Flavonols (kaempeferol,quercetin, myricetin) contents of selected fruits,vegetables and medicinal plants 总被引:1,自引:0,他引:1
The concentrations of flavonols (kaempeferol, quercetin, myricetin) were determined in 22 plant materials (9 vegetables, 5 fruits, and 8 medicinal plant organs). The materials were extracted with acidified methanol (methanol/HCl, 100:1, v/v) and analyzed by reverse phase high-performance liquid chromatographic (RP-HPLC) with UV detection. The total flavonols contents varied significantly (P < 0.05) among vegetables, fruits and medicinal plant organs ranged from 0 to 1720.5, 459.9 to 3575.4, and 2.42 to 6125.6 mg kg−1 of dry matter, respectively. Among vegetables, spinach and cauliflower exhibited the highest amounts of flavonols (1720.5 and 1603.9 mg kg−1, respectively), however, no flavonols were detected in garlic. Within fruits, highest level of flavonols was observed in strawberry (3575.4 mg kg−1), whereas, the lowest in apple fruit (459.9 mg kg−1). Of the medicinal plant organs, moringa and aloe vera leaves contained the highest contents of flavonols (6125.6 and 1636.04 mg kg−1), respectively, whereas, lowest was present in barks (2.42–274.07 mg kg−1). Overall, leafy green vegetables, soft fruits and medicinal plant leaves exhibited higher levels of flavonols. 相似文献
200.
Saima Sultana Rafiuddin 《Journal of Alloys and Compounds》2011,509(41):9842-9848
Superionic conductors were prepared by admixing metallic oxides (alumina and titania) with cadmium iodide in different proportions using direct mixing method. The synthesized materials were characterized by various qualitative techniques such as XRD (X-ray diffraction), DSC (differential scanning calorimetry) and SEM (scanning electron microscopy). Pure CdI2 shows the standard pattern which corresponds to β-phase stable at room temperature, however, the diffractograms of the mixtures shows two phase nature of the materials with no effect of the second phase on the peak positions of the first, i.e. CdI2. DSC curves also confirmed the formation of composite. SEM micrographs show the presence of great number of space charge regions which are very important in creating a great number of surfaces which in turn act as additional sources of point defects. It was also found that the conductivity of CdI2 increases with mole fractions of dopants till x = 0.5 for alumina and x = 0.3 for titania. Arrhenius equation was used to study the temperature dependence of electrical conductivity and the activation energy of pure cadmium iodide was found to be 0.792 eV. 相似文献