191 research outputs found
Electrochemical Redox Processes of Uranium In Aqueous Solutions of Acetylacetone
Electrochemical redox processes of uranium (VI) and uranium
(V) in aqueous solutions of acetylacetone have been studied
by means of various electrochemical techniques.
The presence of acetylacetone accelerates the rate of disproportionation
of uranium (V), even under conditions such that
uranium (VI) is not in the form of the acetylacetonato complex.
The corresponding rate constants of disproportionation were determined.
The influence of the acetylacetonato ion concentration on the
potential and on the rate of the uranium (VI) - uranium (V) electron
transfer was investigated by means of cyclic voltammetry and
squa,re-wave polarography. Both reduction and oxidation of uranium (V) were investigated by using the Kalousek commutator technique. A mechanism for those processes is proposed.
It was proved by electrocapillary measurements that besides
the adsorption of acetylacetone, adsorption of several uranium
acetylacetonato species plays an important role in the overall
mechanism. Taking into account the experimental results, the redox processes of uranium (VI) and uranium (V) in the presence of acetylacetone can be explained in terms of an ECE mechanism
Electrochemical Redox Processes of Uranium In Aqueous Solutions of Acetylacetone
Electrochemical redox processes of uranium (VI) and uranium
(V) in aqueous solutions of acetylacetone have been studied
by means of various electrochemical techniques.
The presence of acetylacetone accelerates the rate of disproportionation
of uranium (V), even under conditions such that
uranium (VI) is not in the form of the acetylacetonato complex.
The corresponding rate constants of disproportionation were determined.
The influence of the acetylacetonato ion concentration on the
potential and on the rate of the uranium (VI) - uranium (V) electron
transfer was investigated by means of cyclic voltammetry and
squa,re-wave polarography. Both reduction and oxidation of uranium (V) were investigated by using the Kalousek commutator technique. A mechanism for those processes is proposed.
It was proved by electrocapillary measurements that besides
the adsorption of acetylacetone, adsorption of several uranium
acetylacetonato species plays an important role in the overall
mechanism. Taking into account the experimental results, the redox processes of uranium (VI) and uranium (V) in the presence of acetylacetone can be explained in terms of an ECE mechanism
Electrochemical oscillations and bistability during anodic dissolution of vanadium electrode in acidic media—part II. The model
Sampled-Current Voltammetry at Microdisk Electrodes: Kinetic Information from Pseudo Steady State Voltammograms
Covalent enzyme coupling on cellulose acetate membranes for glucose sensor development
International audienceMethods for immobilizing glucose oxidase (GOx) on cellulose acetate (CA) membranes are compared. The optimal method involves covalent coupling of bovine serum albumin (BSA) to CA membrane and a subsequent reaction of the membrane with GOx, which has previously been activated with an excess of p-benzoquinone. This coupling procedure is fairly reproducible and allows the preparation of thin membranes (5-20 µm) showing high surface activities (1-3 U/cm2) which are stable over a period of 1-3 months. Electrochemical and radiolabeling experiments show that enzyme inactivation as a result of immobilization is negligible. A good correlation between surface activity of membranes and their GOx load is observed
Risk-based prioritization of pharmaceuticals in the natural environment in Iraq
Numerous studies have demonstrated the occurrence of pharmaceuticals in the natural environment, raising concerns about their impact on non-target organisms or human health. One region where little is known about the exposure and effects of pharmaceuticals in the environment is Iraq. Due to the high number of pharmaceuticals used by the public health sector in Iraq (hospitals and care centres) and distributed over the counter, there is a need for a systematic approach for identifying substances that should be monitored in the environment in Iraq and assessed in terms of environmental risk. In this study, a risk-based prioritization approach was applied to 99 of the most dispensed pharmaceuticals in three Iraqi cities, Baghdad, Mosul and Basrah. Initially, information on the amounts of pharmaceuticals used in Iraq was obtained. The top used medicines were found to be paracetamol, amoxicillin and metformin with total annual consumption exceeding 1000 tonnes per year. Predicted environmental concentrations (PECs) and predicted no-effect concentrations (PNECs), derived from ecotoxicological end-points and effects related to the therapeutic mode of action, were then used to rank the pharmaceuticals in terms of risks to different environmental compartments. Active pharmaceutical ingredients used as antibiotics, antidepressants and analgesics were identified as the highest priority in surface water, sediment and the terrestrial environment. Antibiotics were also prioritized according to their susceptibility to kill or inhibit the growth of bacteria or to accelerate the evolution and dissemination of antibiotic-resistant genes in water. Future work will focus on understanding the occurrence, fate and effects of some of highly prioritized substances in the environment
Perspectives on utilization of edible coatings and nano-laminate coatings for extension of postharvest storage of fruits and vegetables
It is known that in developing countries, a large quantity of fruit and vegetable losses results at postharvest and processing stages due to poor or scarce storage technology and mishandling during harvest. The use of new and innovative technologies for reducing postharvest losses is a requirement that has not been fully covered. The use of edible coatings (mainly based on biopolymers) as a postharvest technique for agricultural commodities has offered biodegradable alternatives in order to solve problems (e.g., microbiological growth) during produce storage. However, biopolymer-based coatings can present some disadvantages such as: poor mechanical properties (e.g., lipids) or poor water vapor barrier properties (e.g., polysaccharides), thus requiring the development of new alternatives to solve these drawbacks. Recently, nanotechnology has emerged as a promising tool in the food processing industry, providing new insights about postharvest technologies on produce storage. Nanotechnological approaches can contribute through the design of functional packing materials with lower amounts of bioactive ingredients, better gas and mechanical properties and with reduced impact on the sensorial qualities of the fruits and vegetables. This work reviews some of the main factors involved in postharvest losses and new technologies for extension of postharvest storage of fruits and vegetables, focused on perspective uses of edible coatings and nano-laminate coatings.María L. Flores-López thanks Mexican Science and Technology Council (CONACYT, Mexico) for PhD fellowship support (CONACYT Grant Number: 215499/310847). Miguel A. Cerqueira (SFRH/BPD/72753/2010) is recipient of a fellowship from the Fundação para a Ciência e Tecnologia (FCT, POPH-QREN and FSE Portugal). The authors also thank the FCT Strategic Project of UID/ BIO/04469/2013 unit, the project RECI/BBB-EBI/0179/2012 (FCOMP-01-0124-FEDER-027462) and the project ‘‘BioInd Biotechnology and Bioengineering for improved Industrial and AgroFood processes,’’ REF. NORTE-07-0124-FEDER-000028 Co-funded by the Programa Operacional Regional do Norte (ON.2 – O Novo Norte), QREN, FEDER. Fundação Cearense de Apoio ao Desenvolvimento Científico e Tecnológico – FUNCAP, CE Brazil (CI10080-00055.01.00/13)
Interdependence between transportation system and power distribution system: a comprehensive review on models and applications
The rapidly increasing penetration of electric vehicles in modern metropolises has been witnessed during the past decade, inspired by financial subsidies as well as public awareness of climate change and environment protection. Integrating charging facilities, especially high-power chargers in fast charging stations, into power distribution systems remarkably alters the traditional load flow pattern, and thus imposes great challenges on the operation of distribution network in which controllable resources are rare. On the other hand, provided with appropriate incentives, the energy storage capability of electric vehicle offers a unique opportunity to facilitate the integration of distributed wind and solar power generation into power distribution system. The above trends call for thorough investigation and research on the interdependence between transportation system and power distribution system. This paper conducts a comprehensive survey on this line of research. The basic models of transportation system and power distribution system are introduced, especially the user equilibrium model, which describes the vehicular flow on each road segment and is not familiar to the readers in power system community. The modelling of interdependence across the two systems is highlighted. Taking into account such interdependence, applications ranging from long-term planning to short-term operation are reviewed with emphasis on comparing the description of traffic-power interdependence. Finally, an outlook of prospective directions and key technologies in future research is summarized.fi=vertaisarvioitu|en=peerReviewed
Enhancement of oxygen reduction at Co-porphyrin catalyst by supporting onto hybrid multi-layered film of polypyrrole and polyoxometalate-modified gold nanoparticles
Effect of the Addition of Carnauba Wax on Physicochemical Properties of Chitosan Films
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