Comparison of antioxidant capacity and phenolic composition of peel and flesh of some apple varieties

BACKGROUND: Apples contain a large concentration of phenolic compounds, dependent on factors such as cultivar, harvest, storage conditions, and processing. This study aims to identify the essential phenolic compounds present in various apple varieties, to measure their total antioxidant capacity (TAC) with the CUPRAC (cupric ion reducing antioxidant capacity) and ABTS (2,2′‐azino‐bis(3‐ethylbenzothiazoline‐6‐sulfonate)) methods, and to correlate their TAC values with HPLC findings. RESULTS: The order of TAC (mmol Trolox g^?1 fresh weight) of apple peels determined with the CUPRAC method was: Granny Smith > Amasya > Sky Spur > Ervin Spur > King Luscious ≥ Arap Kizi ≥ Lutz Golden. The theoretically calculated TAC values of HPLC‐quantified compounds, with the aid of the combined HPLC‐CUPRAC method, accounted for 18.4–33.5% of the experimentally observed CUPRAC capacity of peel extracts and 19.5–56.3% of flesh extracts, depending on apple variety. CONCLUSION: In synthetic samples of apple antioxidants, the CUPRAC‐TAC values of constituents, identified and analyzed by HPLC, proved to be additive, enabling measurement of the cooperative action of antioxidants using the proposed methodology. Apple peel showed higher contents of phenolics and therefore higher TAC than apple flesh, confirming the health benefit of the consumption of apples together with peel. © 2012 Society of Chemical Industry     

Comparison of total antioxidant capacity and phenolic composition of some apple juices with combined HPLC–CUPRAC assay

It was aimed in this study to identify and quantify various constituents (particularly phenolics) of apple juice and to quantitatively compare the total antioxidant capacities of juices obtained from apple varieties grown in Turkey.     

Empirical Correlations for Estimating Filtrate Volume of Water Based Drilling Fluids

Standard American Petroleum Institute (API) filter press is generally used for identifying the filtrate volume of drilling fluids and works only at very low pressures. In fact, during a drilling operation, at downhole conditions, the pressures encountered are significantly higher than what is used during standard API filter press tests. A relationship between the well-known fluid properties and the filtrate volume test is developed. In this study, experiments have been conducted for different water-clay mixtures with varying concentrations at different pressure values by using standard API filter press and HP&HT (high-pressure high-temperature) filter press. The relationship between physical and chemical properties of water-clay mixtures and filtrate volume is analyzed. An empirical correlation has been developed for estimating filtrate volume using basic information of the mud (i.e., rotational viscometer readings, density, pressure, cation exchange capacity, and chemical composition). The developed correlation can estimate filtrate volume with an error less than 20% for a wide range of pressure values.     

Artificial neural networks compared to factor analysis for low-dimensional classification of high-dimensional body fat topography data of healthy and diabetic subjects.

Subcutaneous adipose tissue thickness was measured in 590 healthy subjects at 15 specific body sites by means of the new optical device, lipometer, providing a high-dimensional and partly highly intercorrelated set of data, which had been analyzed by factor analysis previously. N-2-N back-propagation neural networks are able to perform low-dimensional display of high-dimensional data as a special application. We report about the performance of such a 15-2-15 network and compare its results with the output of factor analysis. As test data for verification, measurement values on women with proven diabetes mellitus type II (NIDDM) are used. Surprisingly our 15-2-15 neural network is able to reproduce the classification pattern resulting from factor analysis very precisely. After extracting the network weights the classification of new subjects is even more simple with the neural network as compared with factor analysis. In addition, the network weights are able to cluster highly correlated body sites nicely to different groups, corresponding to different regions of the human body. Thus, the analysis of these weights provides additional information about the structure of the data. Therefore, N-2-N networks seem to be a good alternative method for analyzing high-dimensional data with strong intercorrelation.     

Changes in water content of high plus hydrogel lenses worn on an extended wear basis in a geriatric aphakic population.

PURPOSE: To investigate the water content of hydrogel lenses of relatively high plus power hydrogel lenses after 3 months extended wear and compare values with unused lenses. METHOD: Geriatric aphakic extended wear soft lens patients were fitted with one of four different brands of hydrogel lenses (A) Incanto 78 (Cantor and Nissel, UK), (B) PSL72 (Prospect lenses, UK), (C) ES70 (Ocular Sciences), (D) Proclear (Coopervision). After 3 months continuous wear the lens was removed and water content (WC) was determined at both lens surfaces using an Abbé refractometer. The water content was also measured for 40 unused lenses (+10 to +20D, 10 lenses per brand). RESULTS: One hundred and thirty-two lenses were checked after 3 months extended wear. Mean (+/-S.D.) WC values for front (f) and back (b) surfaces of worn and unworn lenses were, respectively, (A) Worn (n=45): f 73.2(4.13) b 73.8(4.33); unworn f 80.5(0.68) b 81.1 (0.80). (B) Worn (n=37); f 70.5(4.49) b 70.9 (3.89); unworn f 72.5(0.94) b 72.3 (0.89). (C) Worn (n=34); f 68.3(3.18) b 68.4(3.63); unworn f 70.6 (0.48) b 71.1 (0.55). (D) Worn (n=16); f 63.4(3.68) b 63.3(3.19); unworn f 60.9 (1.56) b 61.5 (1.92). There was a significant correlation between WC measured from front and back surfaces (p < 0.01). In worn A-C lenses, front surface WC tended to be lower than back surface WC. For lenses A and C at both surfaces the WC of worn lenses was significantly lower than unworn lenses (p < 0.05). For lens D, mean WC of worn lenses was significantly higher than unworn lenses (p < 0.05). In 80% of B lenses, surface WC of worn lenses were significantly lower than WC of unworn lenses (p < 0.05). There was no relationship between WC and lens power. CONCLUSION: On average, A and C lenses tended to desiccate but D lenses tended to swell as did 20% of B lenses. The front surface of worn lenses measured lower water content than the back surface suggesting the front surface is drier than the back. This apparent difference in water content between the surfaces could be an artefact emanating from differential rates of surface deposition.     

tert-Butylhydroquinone as a spectroscopic probe for the superoxide radical scavenging activity assay of biological samples

As a more convenient and less costly alternative to electron spin resonance (ESR) and nonspecific nitroblue tetrazolium (NBT) and cytochrome c assays of superoxide radical (SR, O(2)(?-)) detection, a novel probe, tert-butylhydroquinone (TBHQ), is introduced for SR nonenzymatically generated in the phenazine methosulfate-β-nicotinamide adenine dinucleotide (PMS-NADH) system. SR attacks both TBHQ and SR scavengers incubated in solution for 30 min where scavengers compete with TBHQ for the O(2)(?-) produced. TBHQ, but not its O(2)(?-) oxidation product, tert-butyl-1,4-benzoquinone (TBBQ), is responsive to the CUPRAC (cupric reducing antioxidant capacity) spectrophotometric assay. The CUPRAC absorbance of the ethyl acetate extract of the incubation solution arising from the reduction of Cu(II)-neocuproine reagent by the remaining TBHQ was higher in the presence of O(2)(?-) scavengers (due to less conversion to TBBQ), the difference being correlated to the SR scavenging activity (SRSA) of the analytes. With the use of this reaction, a kinetic approach was adopted to assess the SRSA of amino acids, vitamins, and plasma and thiol antioxidants. This assay, applicable to small-molecule antioxidants and tissue homogenates, proved to be efficient for cysteine, uric acid, and bilirubin, for which the widely used NBT test is nonresponsive. Thus, conventional problems of NBT assay arising from formazan insolubility and direct reduction of NBT by tested scavengers were overcome.     

Furnace smelting and extractive metallurgy of red mud: Recovery of TiO2, Al2O3 and pig iron

Turkish red mud (bauxite waste) has been mixed with dolomite and coke, pelletized and sintered at 1100°C, and finally smelted at 1550°C to produce pig iron and a slag. The slag was leached with 30% H₂SO₄ at 90°C. The leachate was diluted, ferric iron was reduced with SO₂, and extracted with 5% D2EHPA solution in kerosene. Silica and Al₂O₃ were recovered from the remaining aqueous solution, while the organic extract was stripped with 10% Na₂CO₃ solution, finally hydrolysed and calcined to produce pigment-grade TiO₂. The titanium recovery efficiency on the basis of slag weight was 84·7%. The extractive separation of titanium from both valencies of iron was investigated as a function of pH and time. A stoichiometric flowsheet for the whole process has been developed. ©1997 SCI     

Photooxidation of Some Mono-, Di-, and Tri-chlorophenols in Aqueous Solution by Hydrogen Peroxide/UV Combinations

A number of chlorophenols, namely 2-, 3-, and 4-chlorophenol, 2,4-dichlorophenol and 2,4,6-trichlorophenol, have been decomposed in aqueous solution by using hydrogen peroxide as the oxidizing agent under UV radiation emitted by a 400 W high-pressure mercury lamp in a thermostatted Pyrex-glass column photoreactor, and the organic-bound chlorine has been converted into the environmentally harmless inorganic chloride. For H₂O₂/chlorophenol mole ratios between 1: 1 and 16: 1, the photooxidation reaction approached pseudo-first order kinetics, and the rate constants increased with increasing ratio of the oxidant. A theoretical model for the degradation pathway is proposed. The fact that the reaction order was not simply unity could be attributed to the complex reaction sequence processing via a radical mechanism through colored intermediates possibly comprising hydroquinone, catechol and resorcinol.     

Renewable hydrogen energy regulations,codes and standards: Challenges faced by an EU candidate country

The European Union is one of the most important players in the field of world energy with an integrated and well-organized energy market. However, energy policies in the EU are not sustainable. The EU is the world’s largest importer of fossil fuels and is leading global action in accelerating the transition to renewable energy and low-carbon economy at present. Renewables make the second-largest contribution to domestic energy production after coal.