Phenol degradation using 20, 300 and 520 kHz ultrasonic reactors with hydrogen peroxide, ozone and zero valent metals

The extent of phenol degradation by the advanced oxidation process in the presence of zero valent iron (ZVI) and zero valent copper (ZVC) was studied using 20, 300 and 520 kHz ultrasonic (US) reactors. Quantification of hydrogen peroxide has also been performed with an aim of investigating the efficacy of different sonochemical reactors for hydroxyl radical production. It has been observed that the 300 kHz sonochemical reactor has the maximum efficacy for hydroxyl radical production. Phenol degradation studies clearly indicate that degradation of phenol is intensified in the presence of the catalyst and hydrogen peroxide, which can be attributed to enhanced production of hydroxyl radicals in the system. Experimental data shows that with ZVI, when the reaction was subjected to 300 kHz, complete phenol removal and 37% TOC mineralization was achieved within 25 min, whereas, in the case of 20 kHz US treatment no phenol was detected after 45 min and 39% TOC mineralization was observed. This novel study also investigated the use of zero valent copper (ZVC) and results showed that with 20, 300 and 520 kHz ultrasonic rectors, phenol removal was 10–98%, however, the maximum TOC mineralization achieved was only 26%. A comparative study between hydrogen peroxide and ozone as a suitable oxidant for Fenton-like reactions in conjunction with zero valent catalysts showed that an integrated approach of US/Air/ZVC/H2O2 system works better than US/ZVC/O3 (the ZOO process)

Multi-epoch intra-night optical monitoring of 8 radio-quiet BL Lac candidates

For a new sample of 8 weak-line-quasars (WLQs) we report a sensitive search in 20 intranight monitoring sessions, for blazar-like optical flux variations on hour-like and longer time scale (day/month/year$-$like). The sample consists exclusively of the WLQs that are not radio$-$loud and have either been classified as `radio-weak probable BL Lac candidates' and/or are known to have exhibited at least one episode of large, blazar$-$like optical variability. Whereas only a hint of intra$-$night variability is seen for two of these WLQs, J104833.5$+$620305.0(z = 0.219) and J133219.6$+$622715.9 (z = 3.15), statistically significant inter$-$night variability at a few per cent level is detected for three of the sources, including the radio-intermediate WLQ J133219.6$+$622715.9 (z = 3.15) and the well known bona$-$fide radio$-$quiet WLQs J121221.5$+$534128.0 (z = 3.10) and WLQ J153259.9$-$003944.1 (z = 4.62). In the rest$-$frame, this variability is intra-day and in the far$-$UV band. On the time scale of a decade, we find for three of the WLQs large brightness changes, amounting to 1.655$\pm$0.009, 0.163$\pm$0.010 and 0.144$\pm$0.018 mag, for J104833.5$+$620305.0, J123743.1$+$630144.9 and J232428.4$+$144324.4, respectively. Whereas the latter two are confirmed radio-quiet WLQs, the extragalactic nature of J104833.5$+$620305.0 remains to be well established, thanks to the absence of any feature(s) in its available optical spectra. The present study forms a part of our ongoing campaign of intranight optical monitoring of radio quiet weak-line quasars, in order to improve the understanding of this enigmatic class of Active Galactic Nuclei and to look among them for a possible tiny, elusive population of radio-quiet BL Lacs.Comment: Accepted to MNRAS. 12 pages, 1 figure, 4 Tabl

Stability of Coalescence Hidden variable Fractal Interpolation Surfaces

In the present paper, the stability of Coalescence Hidden variable Fractal Interpolation Surfaces(CHFIS) is established. The estimates on error in approximation of the data generating function by CHFIS are found when there is a perturbation in independent, dependent and hidden variables. It is proved that any small perturbation in any of the variables of generalized interpolation data results in only small perturbation of CHFIS. Our results are likely to be useful in investigations of texture of surfaces arising from the simulation of surfaces of rocks, sea surfaces, clouds and similar natural objects wherein the generating function depends on more than one variable

Why some community forests are performing better than others: a case of forest user groups in Nepal

Management of many Nepalese forests has been devolved to local communities. Forest products, which are used by the community and which may also be traded, are essential contributors to community well-being. Forests are also important contributors of ecosystem services, such as flood protection and wildlife habitat. Nepalese communities were surveyed to measure flows of forest products from their community forests. A stochastic frontier analysis shows that communities are not producing forest products efficiently and there is potential for improvement. The results shows that forest products benefit and environmental performance are associated products. In addition, analysis reveals that factors such as social capital, support from government and knowledge in management contributes positively to the production efficiency. It is anticipated that these findings will contribute to community forest policy redesign and consequently to the welfare of communities.Community forestry, stochastic frontier, production efficiency, Nepal, Community/Rural/Urban Development, Environmental Economics and Policy, Farm Management, Productivity Analysis,

MULTILATERAL GOVERNANCE OF FISHERIES: MANAGEMENT AND COOPERATION IN THE WESTERN AND CENTRAL PACIFIC TUNA FISHERIES

The tuna resources of the Western and Central Pacific are the world's largest and most valuable fisheries of their type and are of significant economic importance to the Pacific island countries through whose waters they migrate. Two major concerns exist with the current governance of this fishery. First, Pacific island countries receive only a small share of the resource rents from the tuna fisheries. Second, the current management structure of the fisheries will not ensure the long-term sustainability of the resources. This paper derives a model to show that the sustainability of the resource can be improved when a single policymaker acts as Stackelberg leader and sets a tax, or an equivalent quantity instrument, to maximize rents from the resource. A practical institutional mechanism is presented that mimics the model's rent maximization outcome and that offers substantial benefits to both Pacific island countries and distant water fishing nations.Resource /Energy Economics and Policy,

Optimisation of abrasive wear of rice husk reinforced epoxy composite by using response surface methodology

Wear is the disintegration or sideways uprooting of a material from its "derivative" and unique position on a solid surface performed by the movement of an alternate surface. The requirement for relative movement between two surfaces and mechanical contact between asperities is a paramount refinement between mechanical wear contrasted with different courses of action with comparative results. The wear analysis is possible by expository procedures like Response Surface Methodology. Response Surface Methodology (RSM) is an accumulation of statistical and mathematical techniques helpful for creating, enhancing, and upgrading methodologies. It additionally has important requisitions in the outline, advancement, and definition of new items, and also in the change of existing item plans. The broadest provisions of RSM are in the modern world, especially in circumstances where several input variables conceivably impact some performance measure or quality characteristic of the product or process