Genotoxic effect induced by hydrogen peroxide in human hepatoma cells using comet assay

Background: Hydrogen peroxide is a common reactive oxygen intermediate generated by variousforms of oxidative stress. Aims: The aim of this study was to investigate the DNA damage capacity ofH2O2 in HepG2 cells. Methods: Cells were treated with H2O2 at concentrations of 25 μM or 50 μM for5 min, 30 min, 40 min, 1 h or 24 h in parallel. The extent of DNA damage was assessed by the cometassay. Results: Compared to the control, DNA damage by 25 μM and 50 μM H2O2 increasedsignificantly with increasing incubation time up to 1 h, but it was not increased at 24 h. Conclusions:Our Findings confirm that H2O2 is a typical DNA damage inducing agent and thus is a good modelsystem to study the effects of oxidative stress. DNA damage in HepG2 cells increased significantlywith H2O2 concentration and time of incubation but later decreased likely due to DNA repairmechanisms and antioxidant enzyme

Value added products from vineyard wastes - a review

Grape pomace is about 10% by weight of the grape input and consists of pressed skins, disrupted cells from grape pulp, seeds and stems. Grape pomace is mainly used as cattle feed or for soil conditioning or dumped in disposal sites. Cell walls of grape pomace are composed of cellulose, hemicelluloses, pectin and lignin arranged in a complex network. Lignin constitutes about 38-40% of the total grape pomace mass. Grape pomace is rich in polyphenols, fibres, tannins, tartaric acid, citric acid, anthocyanin and neutral sugars. Pomace can be separated in to marc (skin and pulp) and seeds in a breaker. Grape marc constituted mainly industrial source of anthocyanin based colorants. Grape seeds are a complex matrix containing approximately 40% fibre, 16% oil, 11 % proteins and 7% complex phenols including tannins in addition to sugars and mineral salts. The seeds of the grapes contain about 8-22% edible oil and the seed oil has been identified as a potential product because of its low saturated fats content and its high concentration (70-75%) of linoleic acid. Grape pomace is rich in phenolic compounds and the interest in phenolic compounds are from their antioxidant properties and their ability to serve as free radical scavengers. Grape seed extracts are reported to possess anticancer, antiulcer, anticataract and antiarteriosclerosis effect. In conclusion grape pomace, the byproduct of wine industry has a huge potential for the isolation of compounds in food preservation as well as for nutraceuticals and therapeutic agents

Enhanced degradation of waste grass clippings in one and two stage anaerobic systems

The present work investigated the use of a simple rumen-fluid-inoculated anaerobic treatment system for the degradation of organic waste. Fresh rumen fluid collected from a fistulated sheep was used as the inoculum and fresh grass clippings were used as the waste material for treatment. Studies were carried out on both a one-stage system where the ligno-cellulosic fraction breaks down into a mixture of soluble products including volatile fatty acids and a two- stage system where these products are subsequently mineralised to biogas. In the one stage system about 70% of the organic waste was solubilized and in the two stage system about 60% waste material was solubilized in a week. About 50% of the degradation was achieved in a 4 day period, showing that a 4 day solids retention time would be a suitable operating regime. The maximum volatile fatty acid production rate was 327 mg COD 1 -1 h -1. A higher loading rate of 30 g 1 -1 d -1 was achieved in these systems compared to anaerobic digesters. Microbiological studies showed an increase in the number of fungal spores as well as a decrease in the number of protozoa in the treatment system. These numbers attained stable values over the duration of the experiments. The system developed is superior to conventional composting or anaerobic digestion and can be applied for the treatment of ligno-cellulosic agricultural residues

Effect of recirculated leachate volume on MSW degradation

Landfilling represents the most economical method for the disposal of municipal solid waste (MSW). After depletion of the limited volume of air available in void spaces of a waste bed, decomposition in a landfill takes place under anaerobic conditions. Anaerobic digestion requires moisture and a lack of water is generally responsible for retarding degradation of MSW in conventional landfills. Furthermore, the moisture that may be present is seldom uniformly distributed. Bioreactor landfills are being researched as a means to provide a rapid and predictable stabilisation of waste and landfill gas production. This is achieved primarily by control and management of the liquid flow within the landfill. The moisture content of waste and moisture movement through a waste bed are two distinct factors that affect MSW decomposition. A moist environment is critical for microbial activity; and flow of moisture is essential to mobilize nutrients and evenly distribute microorganisms through a waste bed. The movement of moisture through a waste bed also provides improved mass transfer and prevents the development of stagnant zones. Experiments were carried out to understand how the amount of recirculated leachate effects waste degradation in coupled pairs of stabilised and fresh waste reactors. Higher recirculation rates are shown to both improve solubilisation of fresh waste, and also establish the methanogenic microbial population more quickly. In the best case, the organic fraction of the waste was essentially entirely degraded within 2 months

Combining Active- and Passive-Source Measurements to Profile Shear Wave Velocities for Seismic Microzonation

A surface wave measurement made by combining active- and passive- source methods was adopted to characterize shear wave velocity (VS) profiles at a dozen sites around the Las Vegas basin for the purpose of seismic microzonation. The active- and passive-source methods used were the SASW and ReMi methods, respectively. The dispersion datasets developed by both methods for the same location generally exhibited excellent agreement. They are supplementary to one another in that the active-source measurement provides detailed information at shallower depths but depth of resolution is constrained by the capability of the seismic source, while the passive-source measurement yields a greater depth of resolution but provides less detail at shallower depths. The VS profiles were developed by inverting the combined dispersion dataset using simulated annealing followed by linearized inversion. Trends in overall VS for each site tend to be inversely related to basin depth, which is appropriate based on lithologic cues

Comparing the concentration of calcium hydroxide in the diffuse double layer by modeling and experiment

The leaching of elements from the surface of charged fly ash particles is known to be an unsteady process. The mass transfer resistance provided by the diffuse double layer has been quantified as one of the reasons for this delayed leaching. In this work, a model based on mass transfer principles for predicting the concentration of calcium hydroxide in the diffuse double layer is presented. The significant difference between predicted calcium hydroxide concentration and the experimentally measured is explained

Optimal and suboptimal control of anaerobic digesters

Anaerobic digester failure due to entry of inhibitors or sudden changes in the feed substrate concentration may be encompassed beneficially by applying optimal control theory. An almost proportional relationship between the dilution rate and the methane production rate leads to a simple suboptimal control law with only minor loss in performance, after the occurrence of the above mentioned events