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Managing certain by-products of the nuclear fuel cycle, such as the radioactive isotopes of caesium: 134Cs, 135Cs and 137Cs is challenging due to their environmental mobility and radioactivity. While a great many materials can isolate Cs+ ions from neutral or basic aqueous solutions via ion exchange, few of these, with the exception of ammonium phosphomolybdate (AMP), function effectively in acidic media. The use of AMP, and its porous composite in polyacrylonitrile (PAN) for management of Cs radioisotopes in various nuclear wastes have been known for decades and are well studied, yet the effects of radiation on the physiochemical properties of such composites have only received limited attention to date. In a previous publication, we demonstrated that a 100 kGy gamma irradiation dose has negligible effect on the ion exchange performance of AMP and AMP&ndash, PAN with respect to capacity or kinetics under the Cs+ concentrations and acidity found in spent nuclear fuel (SNF) recycling. As a continuation of this prior study, in this publication we explore the effects of gamma irradiation on the physiochemical properties of AMP and AMP&ndash, PAN using a range of characterisation methods. The effects of the same gamma dose on the oxidation state of Mo in AMP and AMP&ndash, PAN, the thermal degradation of both AMP and AMP&ndash, PAN, combined with a first study into the high-temperature degradation AMP, are reported. The implications of irradiation, its possible mechanism, the conditions present in SNF recycling, and for the end-of-life disposal or recycling of these materials are also discussed.

Due to their acid characteristics and pore structure, which can induce high product selectivity; zeolite catalysts are used extensively in industry to catalyse reactions involving hydrocarbons. However, these catalysts can suffer from deactivation due to cracking reactions that result in the deposition of carbon leading to poisoning of the acid sites and blocking of the pores [1]. Depending upon the reaction and the particular catalyst involved this deactivation may take place over several months or even years but in some cases occurs in minutes. Therefore, zeolite catalysts are frequently reactivated / regenerated. This generally involves a thermal treatment involving air which results in oxidation of the carbon [2]. However, the oxidation of carbon is highly exothermic, and if not carefully controlled, results in the generation of exceedingly high localized temperatures which can destroy the zeolite structure and result in subsequent loss of catalyst activity. More conservative thermal treatments can result in incomplete regeneration and again a catalyst displaying inferior activity. This paper explores the use of non-thermal plasma which had been either generated using microwaves or via a barrier discharge to regenerate spent zeolite catalysts. The catalyst, H-mordenite, was tested for the disproportionation of toluene (Figure 1) using conventional heating. The spent catalyst was then regenerated using a plasma or conventional thermal treatment before having its activity re-evaluated for the toluene disproportionation reaction as previous. Fig. 1. Reaction Scheme for Toluene Disproportionation. Interestingly, not only is plasma regeneration highly effective but also catalysts can be regenerated in greatly reduced times. There is an additional advantage in that plasma regeneration can impart physical properties that result in a zeolite that is resistant to further deactivation. However, the results are highly dependent upon the experimental conditions involved for plasma regeneration. References Wu J, Leu L., Appl. Catal., 1983; 7 :283-294. M. Guisnet and P. Magnoux, Deactivation of Zeolites by Coking. Prevention of Deactivation and Regeneration. In: Zeolite Microporous Solids: Synthesis, Structure, and Reactivity. E.G. Derouane, F Lemos, C. Naccache, F. Ramoa Ribeiro, Eds. Pages 437-456. Springer 1992.

This paper addresses the stability of commercial cation exchangers when in contact with nitric acid that are under consideration for UCLan’s alternative reprocessing process. The paper describes the acid tolerance of four commercial ion exchange resins when exposed to 7M nitric acid for one year. The acid degradation was measured by FT-IR and TGA before and post acid exposure. Zirconium uptake was measured pre and post acid exposure as a means of determining degradation of functional sites. The resins undergo a degree of acid degradation depending on their chemical composition i.e., polymeric backbone, in some instances loss of functionality but also the introduction of new functional sites. The likely radiation dose that ion exchange resins would receive from spent nuclear fuel dissolver liquor and from adsorbed radioactive cesium 137 were estimated. It was inferred that the radiation dose the exchangers would receive from adsorbed cesium isotopes would be comparatively low when compared with the radiation background of the spent fuel dissolver liquor.

In a previous publication, the authors described a chromatographic process for the selective separation of fission products and minor actinides from uranium and plutonium in nitric acid solution. This paper has evaluated commercially available ion exchange materials for capacity, rate of uptake and selectivity for some fission products (inactive) and cerium (iii) and (iv) as surrogate for Pu and U. The fission products studied where Cs, Sr and Zr as these for various reasons present major challenges for the existing PUREX process and waste management. The commercial resins evaluated were various sulfonic acid, chelate ion exchangers and an undisclosed inorganic material all supplied by Purolite Ltd.

The synthesis of the high performance inorganic materials essential to the quality of modern day life is hindered by traditionalist attitudes and reliance on outdated methods such as batch syntheses. While continuous flow methods have been extensively adopted in pharmaceutical circles, they remain largely unexplored for the preparation of inorganic compounds, despite higher efficiency, safety and versatility. In this publication, we demonstrate a step-change for the synthesis of metal ammonium phosphates through conversion of the extant batch process to a low-temperature continuous regime, exhibiting a tenfold increase in throughput combined with a significant decrease in particle size.

This concept paper, discusses the challenges and opportunities for an extractive chromatographic process for the separation of fission products and minor actinides from uranium and plutonium isotopes in irradiated nuclear fuel. The paper highlights the constraints of the PUREX process, a process that is universally accepted for reprocessing of spent nuclear fuel now and for GEN IV reactor systems. It also identifies the challenges that a new separation process would have to overcome to dislodge its acceptance by both the operators and regulators. Although the concept of using a chromatography technique for this separation is challenging, recent developments of continuous chromatography such as simulated moving bed (SMB) and/or continuous annular chromatography (CAC) provides a degree of encouragement. Equally the development of new stationary phases in particular inorganic exchangers, many of which have not been examined for this application enhances confidence that an alternative to the PUREX process is possible.

The present work has used microwave plasma chemical vapour deposition to generate suitable isotopically labelled carbonaceous deposits on the surface of Pile Grade A graphite for use as surrogates for studying the behaviour of the deposits observed on irradiated graphite extracted from UK Magnox reactors. These deposits have been shown elsewhere to contain an enhanced concentration of 14C compared to the bulk graphite. A combination of Raman spectroscopy, ion beam milling with scanning electron microscopy and secondary ion mass spectrometry were used to determine topography and internal morphology in the formed deposits. Direct comparison was made against deposits found on irradiated graphite samples trepanned from a Magnox reactor core and showed a good similarity in appearance. This work suggests that the microwave plasma chemical vapour deposition technique is of value in producing simulant carbon deposits, being of sufficiently representative morphology for use in non-radioactive surrogate studies of post-disposal behaviour of 14C-containing deposits on some irradiated Magnox reactor graphite.

The acylation of anisole with decanoic acid over a range of solid-acid catalysts has been studied under conventional heating and microwave stimulation. The microwave-irradiated experiments exhibited increased reaction rates, the extent of which was dependent upon the nature of the catalyst. The origin of this microwave enhancement has been attributed to the selective desorption of water from the surface of the catalyst. Pyridine adsorption has been used to quantify the number of acid sites present on the catalyst. The nature of the acid sites in terms of their Bronsted/Lewis acidity has been determined using infrared analysis of the adsorbed pyridine. The strength of the acid sites has been characterised by differential thermal analysis (DTA) of the pyridine desorption. This indicated that the sulphated zirconia and supported heteropoly acids contained significantly more strong acid sites than the cerium exchanged zeolite.

This paper describes the development of a microwave plasma reactor for the oxidation of gaseous organic contaminants in air. The reactor was designed such that plasma could be sustained at atmospheric pressure or greater with an effluent gas flow rate of up to 2000 l/min. The oxidation of methane was chosen as the test reaction for laboratory studies.

The transformation of an oil shale sample from the Autun Basin in the Massif Central, France, was studied using two different heating strategies: microwave irradiation and conventional heating. Microwave heating was performed using a single-mode cavity operating at a frequency of 2.45 GHz under an inert atmosphere. Heating of the sample generated liquid products of similar composition using either microwave or conventional heating. The yields of liquid products were similar in the two cases, while the overall energy requirements were much lower using microwave irradiation. The influence of water vapor on the oil shale decomposition was also studied under microwave energy. In order to simulate conversion of the organic fraction of the oil shale in the presence of an acidic zeolite catalyst, the oil shale sample was mixed with 5 wt % BEA zeolite and heated under microwave irradiation. It was found that the liquid products yield decreased along with an increase in the amount of coke produced. Gaseous and liquid products recovered showed a tendency for the production of lighter components in the presence of zeolite. The aromatic character of the oils was more important when microwaves were used, especially in the presence of zeolite.

Thermally induced transformations in materials (e.g. melting, decomposition or solid‐solid phase changes) alter their dielectric properties and hence their ability to interact with a microwave field. This paper describes a new technique, microwave thermal analysis, where microwaves are used both to heat a material and as a means of detecting thermal transitions. Two approaches are described. The first is based on the changes in the temperature of a material when subjected to a constant microwave power and the second on the microwave power profile obtained when a material is heated in a controlled (linear) manner. Both approaches can provide qualitative and quantitative information on solid state processes. A classification is proposed for the different types of results found for various materials and transitions. The advantages and limitations of studying transitions and reactions using microwave energy are discussed. # 2000 Elsevier Science B.V. All rights reserved.

This article describes the design and operation of a new thermal analysis instrument which uses microwaves to simultaneously heat and detect thermally induced transformations in samples with masses in the range of 50 mg to 0.5 g. The data acquisition and control software developed for the instrument support a range of experimental techniques including constant power, linearly ramped power, linearly ramped temperature, and various modulated methods. Microwave thermal analysis utilizes the fact that physical or chemical alterations in a material, caused by processes such as melting, decomposition, or solid-solid phase changes, cause variations in its dielectric properties. These can be revealed by a variety of means including changes in the sample temperature, the differential temperature, or the shape of the power profile during linear heating experiments. The scope of the instrument is demonstrated with the decomposition of basic copper carbonate. The large temperature increase (∼100 °C) observed on the formation of the strongly coupling oxide indicates the potential sensitivity of using the thermal effects of dielectric changes as a means of detection. Further fine detail can be revealed by the use of derivative plots of either the applied power or the temperature.

The paper describes microwave differential thermal analysis, a new technique that combines the advantages of microwave heating with the benefits of differential temperature measurement to give a sensitive means of probing the thermal properties of materials as a function of temperature. Details are given of the theoretical background, equipment, design of sample cells, and different modes of operation. Examples are given for a wide range of thermal transitions including fusions, solid−solid phase transitions, and thermal decompositions. The results are discussed in the context of conventional differential thermal techniques.

(1999). 2-METHYLPENTANE (ISOHEXANE) Journal of Toxicology and Environmental Health, Part A: Vol. 58, No. 1-2, pp. 81-92.

Applying research findings to community mental health practices is slowed by provider concerns that research participants often differ from community populations in duration of illness, comorbid conditions, and illness severity. Selecting participants from community settings makes research results demonstrably relevant, but researchers and community providers can be mistrustful of one another, feeling that the other has little understanding of their needs and work. This mistrust impedes patient referrals for research. This column describes a program to increase researcher knowledge of community clinic procedures through structured interactions with clinic personnel. Follow-up interviews indicate improved attitudes and cooperation of researchers and community providers.

This paper describes a new instrument for performing thermal analysis using microwaves both as a form of heating and as a novel means of detecting thermally induced transformations in materials. Results are presented for a selection of processes including decompositions, dehydrations and phase changes. The capability of the instrument to be coupled with ancillary techniques such as EGA is also demonstrated.

Fe-oxide MgO (5–30 mol% Fe) was prepared by calcination of coprecipitated precursors. Reducibility in H 2 at 693 K was measured gravimetrically and volumetrically. All samples yielded metallic iron (Fe o ) suitable for catalytic use but much unreduced Fe 2+ remained, stabilized by the MgO. The mean particle size of the supported metallic iron was determined by X-ray line-broadening and its surface area by CO chemisorption. Mossbauer spectroscopy confirmed the presence of Fe o , Fe 2+ and Fe 3+ in the reduced material.

This article proposes a method for differentiation of biological samples based upon the dielectric characteristics of the sample. Lipid accumulation within cells is significant as it serves as a marker pertaining to the metabolism and oncologic state of the cell and organism. This is accomplished through dielectric characterisation of the sample utilising circuit board based resonant structures. This paper presents a preliminary experiment using lipid accumulating yeast cultures to model lipid droplets in mammalian cells. The experiment indicated that lipid positive and negative cultures can be differentiated based upon the dielectric characteristics of the sample.

This work proposes a novel approach to differentiate biological cells based upon the total concentration of lipids. Lipid accumulation within cells is significant as it serves as a marker pertaining to the metabolism and oncologic state of the cell and organism. This is accomplished through dielectric characterisation of the sample. This chapter presents a preliminary proof of concept experiment using vegetable oils and cell culture media to model lipid droplets in biological cells. The experiment indicated that solutions of numerous different lipid suspensions at different concentrations can be differentiated based upon the dielectric characteristics of the sample. The dielectric constant of vegetable oils was calculated to be between 2.9 and 3.1. The dielectric constant of the suspensions reached up to 27 at a concentration of 0.5% (v/v).

This article proposes a novel method for differentiation of biological cells based upon the total concentration of lipids. Lipid accumulation within cells is significant as it serves as a marker pertaining to the metabolism and oncologic state of the cell and organism. This is accomplished through dielectric characterisation of the sample utilising circuit board based resonant structures. This paper presents a preliminary experiment using lipid accumulating yeast cultures to model lipid droplets in mammalian cells. The experiment indicated that lipid positive and negative cultures can be differentiated based upon the dielectric characteristics of the sample.

Currently, there are no point-of-care diagnosis strategies available to indicate the presence of neoplasmic growth. This research aims to develop a novel diagnostic strategy based on detecting lipid accumulation in various cells. This element of the research is a preliminary experiment to prove the concept of detecting TAG lipid droplets in YEPD media. This method calculated the relative dielectric constant of vegetable oils at 2.991 to 3.014 for groundnut and grapeseed oil respectively. The results indicate a decrease in relative dielectric constant and dielectric loss as the proportion of lipid droplet increases.

The installation and operational characteristics of a titanium element strain gauge pressure sensor in conductivity-temperature-depth (CTD) instruments is described. The behavior of the sensor is examined in both steady state and transient conditions, the latter consisting of thermal shocks achieved in laboratory plunge tests. The titanium pressure sensor has superior linearity and reduced hysteresis as compared with strain gauges which utilize a stainless steel lement. However, significant transient pressure errors are noted for certain gauge installations. A model of the pressure sensor's transient is developed from heat transfer theory, which is solved for an idealization of the Mark III CTD configuration. This, in turn, motivates a numerical procedure for reducing the thermally-induced static and transient pressure error in the titanium strain gauge pressure sensor data, and an installation procedure that thermally isolates the gauge. Residual pressure error in calibrated data from the titanium strain gauge is an acceptably fraction of a decibar.

This article describes a system to investigate the parameters for the remediation of organic vapors using microwave-induced plasma on fluidized carbon granules. The system is based on a single mode microwave apparatus with a variable power (2.45 GHz) generator. Carbon granules are fluidized in a silica tube situated in the sample section of a waveguide incorporating two additional ports to allow plasma intensity monitoring using a light sensor and imaging with a digital camera. A fluoroptic probe is used for in situ measurement of the carbon granule temperature, while the effluent gas temperature is measured with a thermocouple situated in the silica tube outside the cavity. Data acquisition and control software allow experiments using a variety of microwave power regimes while simultaneously recording the light intensity of any plasma generated within the carbon bed, together with its temperature. Evaluation using two different granular activated carbons and ethyl acetate, introduced as a vapor into the fluidizing air stream at a concentration of 1 ppm, yielded results which indicated that significant destruction of ethyl acetate, as monitored using a mass spectrometer, was achieved only with the carbon granules showing high plasma activity under pulsed microwave conditions. The system is therefore suitable for comparison of the relative microwave activities of various activated carbon granules and their performance in microwave remediation and regeneration.

An improved micro-reactor cell for IR spectroscopic studies of heterogeneous catalysis was built around a 5.8 GHz microwave cavity. The reactor can operate at 20 bars and with conventional heating up to 720 K, with reactant gas flows velocities (GHSV) from 25,000 to 50,000 h(-1). The temperature of the sample under microwave irradiation was measured by time resolved IR emission spectroscopy. The first experiment performed was the IR monitoring of the desorption of carbonates induced by irradiating an alumina sample by microwaves at 5.8 GHz.

Fi/MgO catalysts with 5 to 30 mol % Fe have been prepared by impregnation and coprecipitation. Their reducibility has been measured and a comparison made of their Feo surface areas. Catalysts prepared via coprecipitation yielded larger iron areas than those via impregnation. The activity and selectivity of the reduced catalysts for the hydrogenation of propanenitrile at 20–30 bar and 473 K and of ethanenitrile at 1 bar and 508 K have been determined. The most active catalysts are those prepared by coprecipitation and they show high selectivity for primary amines. The activity for ethanenitrile hydrogenation correlates with the iron surface area.

Microwave chemistry is an established technique in the synthesis of organic compounds at a frequency of 2.45 GHz. This is considered to be a result of the development of microwave ovens, rather than an objective solution, which maximises efficiency through careful selection of the operating frequency. To obtain a frequency for a dielectric, the complex permittivity should be determined as a function of frequency. If the correct heating frequency is found, superheating can occur when a liquid solvent reaches its boiling point and exceeds it. This paper presents sensor diodes and temperature sensors used in a mono-mode reactor, with computer control of an E-H tuner, frequency and incident power to control temperature and power, experimental results showing heating and reactions using ethanol are reported.

Vital inroganic materials are often inefficienty prepared in terms of time, reagents, and manpower. Hydrothermal methods in particular often take many days or even weeks to prepare the desired materials. In this communication, we demonstrate a novel heterogeneous, green synthesis route and the crystal lattice parameters of several pure and intermediate ammonium and potassium titanyl phosphates, representing a significant improvement over existing syntheses in reaction time and precursors used.

There are currently no point-of-care diagnosis strategies available to indicate the presence of neoplasmic growth. This research aims to develop a novel diagnostic strategy based on detecting TAG accumulation in cells. This element of the research is a preliminary experiment to prove the concept of detecting TAG lipid droplets in YEPD media. It was found that a change in mono-unsaturated concentration can be detected by the frequency shift in a resonant cavity. The dielectric constant of TAG vegetable oils was calculated at 2.34-2.39. It was also found that concentrations of lipid droplet can be differentiated up to 5% (v/v).