Results 1 - 10 of 4522
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[en] Pennisetum purpureum Schumach. is a weed that is currently spreading rapidly to many parts of the world particularly tropical countries. The abundance of P. purpureum in Malaysia is presently a serious problem. A study was conducted to investigate and evaluate the potential allelopathic effects of P. purpureum on Eleusine indica L. Gaertn. using the aqueous leaf extract and plant debris incorporated into the soil. Low concentrations of the P. purpureum aqueous extract (2%) and debris incorporated into the soil (25/ 500 g) inhibited germination and seedling growth of the bioassay species (E. indica) by >80 %. The responses of the bioassay species to the aqueous extract and debris-incorporated soil were concentration dependent. The aqueous extract had higher total phenolic content compared to that from the debris incorporated soil, indicating the presence of certain phyto toxic compounds in the leaf debris and leaf extracts. (author)
[en] This study aimed to assess the effects of fresh, thermal drying method (vacuum oven drying), and nonthermal drying method (freeze drying) on the antioxidant activities of leaves and berries of Cayratia trifolia using ferric reducing antioxidant power (FRAP) and 1,1-diphenyl-1-picrylhydrazyl radical scavenging capacity (DPPH) assays. The total phenolic content (TPC) and flavonoid content (TFC) of the leaves and berries of C. trifolia were also measured. Based on the results obtained, the TPC, TFC, and antioxidant activities of the leaves and berries were arranged in the following order: freeze-dried sample with methanol extraction > vacuum-dried sample with methanol extraction > freeze-dried sample with water extraction > vacuum-dried sample with water extraction > fresh sample with methanol extraction > fresh sample with water extraction. The results showed a significant difference (p<0.05) between the fresh and dried samples. In conclusion, freeze drying was found to be a good method for maintaining TPC, TFC, and antioxidant activities by FRAP and DPPH methods in the leaves and berries of C. trifolia. (author)
[en] Phenol and its derivatives are among the most prevalent forms of chemical pollutants in the industrial wastewater. The extraction of phenol from acidic solution (pH = 2) with mixtures of tributyl phosphate (TBP) and some selected organic solvents was studied by solvent extraction method. This method has advantages on treating high concentrated phenol wastewater. The most efficient organic solvent, the equilibration extraction time and the optimal concentration of TBP were determined. Furthermore, the transport of phenol through a flat sheet supported liquid membrane (FSSLM) containing a mixture of TBP-kerosene as liquid membrane has been investigated. Complete stripping was achieved using aqueous NaOH solution. The permeation of phenol was carried out by varying the concentration of phenol in feed phase from 100 to 1200 ppm and flux increases from 0,00000177 to 0,0000531 mol.m-2.s-1, respectively. The stability of the membrane system used was also investigated in continuous run showing more than 4 days stability.
[en] Biological concentration and transfer of organic chemicals through aquatic food webs can be influenced by a variety of environmental, biological, and biochemical factors. Bioaccumulation can be significantly altered by the presence of suspended matter or complex organic mixtures in the water column. In addition, the bioaccumulation factor of a compound is dependent on the species of an organism, its life stage, and the available food supply. Metabolic changes in structure of absorbed organics can alter both the rate and the mechanism of absorption and elimination of organics. In the case of quinoline absorption by trout, both the rate of absorption and the metabolic disposition depended upon whether exposure was through ingestion or through direct water column exposure. All of these factors can be used to explain why the physical properties of organic compounds (most notably octanol/water partition coefficients) are unreliable predictors of bioaccumulation potential. 24 refs., 1 tab
[en] The purpose of this study was to determine the effects of convective air- drying at different temperatures (35, 50, 60 and 75°C) on the color of Bifurcaria bifurcata (BB) seaweed powders obtained after milling, the antioxidant activity and polyphenolic and carbohydrate content of the aqueous extracts obtained by ultrasound-assisted extraction. BB seaweed powders exhibited significant color differences between powders obtained from BB dried at 35oC (yellowish-green) and 50–75 °C (brown). High air drying temperature (above 60oC) significantly reduced the total polyphenolic, carbohydrate content and scavenging activity of aqueous extracts of BB. (Author)
[en] Free phenolic hydroxyl content was determined in various parts of oil palm (Elaeis guineensis) such as trunk, frond, mes carp, shell, empty fruit bunch and comparatively evaluated by aminolysis and periodate oxidation methods. This determination will elucidate the reactivity of lignin in oil palm and provide information for its future efficient utilisation. The results showed that aminolysis method consistently yielded higher values for phenolic hydroxyl content than the periodate oxidation method. More phenolic hydroxyl content was observed in the trunk, mesocarp and frond than in the shell and empty fruit bunch. As a comparison, phenolic hydroxyl content was also evaluated for hardwood, Japanese beech (Fagus crenata) and soft wood, Japanese cedar (Cryptomeria japonica) for their sapwood portions. These samples have been selected because of their anatomical differences whereby, under botanical terms, oil palm is classified as one of monocotyledonous angiosperms, Japanese beech is classified as one of dicotyledonous angiosperms and Japanese cedar is classified as gymnosperms. Due to the abrupt increase in the formation of 1-acetylpyrrolidine in the aminolysis method, small discrepancy did exist between aminolysis and periodate oxidation methods, but the trend on the phenolic hydroxyl content was similar. (author)
[en] This work studied the phenolic content, antioxidant activity and the content of vitamin C in different stages of maturity of the fruits of three varieties of guava in Colombia. We worked with two wild varieties, the regional red (RR) and white regional (RB) and a promising character as is the variety Gavata Victory (GV), all from the Suarez river region (Santander, Colombia). Ethanol extracts were obtained and evaluated free phenol content, antioxidant capacity by ABTS and DPPH, frap, bleaching of β-carotene and vitamin C by HPLC. the RB when ripe showed higher value of free phenolic content and antioxidant capacities and best RR was the one with higher value of vitamin C
[en] Table olive processing water (TOPW) contains many complex substances, such as phenols, which could be valorized as a substrate for microalgae biomass culture. The aim of this study was to assess the capability of Nannochloropsis gaditana to grow in TOPW at different concentrations (10- 80%) in order to valorize this processing water. Within this range, the highest increment of biomass was determined at percentage of 40% of TOPW, reaching an increment of 0.36 ± 0.05 mg volatile suspended solids (VSS)/L. Components of algal biomass were similar for the experiments at 10-40% of TOPW, where proteins were the major compounds (56-74%). Total phenols were retained in the microalgae biomass (0.020 ± 0.002 g of total phenols/g VSS). Experiments for 80% of TOPW resulted in a low production of microalgae biomass. High organic matter, nitrogen, phosphorus and phenol removal were achieved in all TOPW concentrations. Although high-value products, such as proteins, were obtained and high removal efficiencies of nutrients were determined, microalgae biomass culture should be enhanced to become a suitable integral processing water treatment.
[es]El agua resultante del proceso de elaboración de la aceituna de mesa (TOPW) presenta un elevado contenido en sustancias complejas, como fenoles, que podría permitir su uso como sustrato para el cultivo de microalgas. El objetivo de este estudio se centra en evaluar la capacidad de crecimiento de annochloropsis gaditana en TOPW a distintas concentraciones (10-80%) con vistas a la valorización de estas aguas. El mayor incremento de biomasa se obtuvo para un porcentaje del 40% de TOPW, alcanzando un aumento de 0.36 ± 0.50 mg sólidos en suspensión volátiles (SSV)/L. Los componentes presentes en la biomasa han sido similares para los experimentos con 10-40% de TOPW, siendo las proteínas los compuestos mayoritarios en todos los casos (56-74%). Los fenoles totales quedaron retenidos en las microalgas, alcanzando una concentración media de 0.020 ± 0.002 g fenoles totales/g SSV. En los experimentos con 80% de TOPW se obtuvieron producciones bajas de microalgas. Las eficiencias de eliminación de materia orgánica, nitrógeno, fósforo y fenoles fueron elevadas para las diferentes concentraciones estudiadas de TOPW. Aunque se ha obtenido una elevada producción de compuestos de interés y altas eficiencias de eliminación de nutrientes, el cultivo de microalgas debería mejorarse para llegar a ser un sistema integral válido para el tratamiento de TOPW.