The PUREX technology based on aqueous processes is currently the leading reprocessing technology in nuclear energy systems. It seems to be the most developed and established process for light water ...reactor fuel and the use of solid fuel. However, demand driven development of the nuclear system opens the way to liquid fuelled reactors, and disruptive technology development through the application of an integrated fuel cycle with a direct link to reactor operation. The possibilities of this new concept for innovative reprocessing technology development are analysed, the boundary conditions are discussed, and the economic as well as the neutron physical optimization parameters of the process are elucidated. Reactor physical knowledge of the influence of different elements on the neutron economy of the reactor is required. Using an innovative study approach, an element priority list for the salt clean-up is developed, which indicates that separation of Neodymium and Caesium is desirable, as they contribute almost 50% to the loss of criticality. Separating Zirconium and Samarium in addition from the fuel salt would remove nearly 80% of the loss of criticality due to fission products. The theoretical study is followed by a qualitative discussion of the different, demand driven optimization strategies which could satisfy the conflicting interests of sustainable reactor operation, efficient chemical processing for the salt clean-up, and the related economic as well as chemical engineering consequences. A new, innovative approach of balancing the throughput through salt processing based on a low number of separation process steps is developed. Next steps for the development of an economically viable salt clean-up process are identified.
The beneficial health effects of extracts from many types of plants that are used as seasoning agents in foods and beverages have been claimed for centuries. The purpose of this study was to examine ...the effectiveness of selected herb and spice essential oils for control of growth and survival of microorganisms. Inhibition of growth was tested by the paper disc agar diffusion method. Antibiotic susceptibility discs were used as control. Minimum lethal concentration (MLC) was determined by the tube dilution method. Essential oils from anise, angelica, basil, carrot, celery, cardamom, coriander, dill weed, fennel, oregano, parsley, and rosemary were evaluated. Inhibition ranged from complete with oregano to no inhibition with carrot oil for each of the test strains that included: Listeria monocytogenes, Staphylococcus aureus, Escherichia coli O:157:H7, Yersinia enterocolitica, Pseudomonas aeruginosa, Lactobacillus plantarum, Aspergillus niger, Geotrichum, and Rhodotorula. Oregano essential oil showed the greatest inhibition (zone, > or = 70 to 80 mm) (MLC, approximately 8 ppm). Coriander and basil were also highly inhibitory (MLC, approximately 25 to 50 ppm) to E. coli O:157:H7 and to the other bacteria and fungi tested. Anise oil was not particularly inhibitory to bacteria (inhibition zone, approximately 25 mm); however, anise oil was highly inhibitory to molds. Because some of the herbal and spice essential oils are highly inhibitory to selected pathogenic and spoilage microorganisms, they may provide alternatives and supplements to conventional antimicrobial additives in foods.
Implantable electrochemical sensors that enable the real-time detection of significant biomarkers offer huge potential for the enhancement and personalisation of therapies; however, biofouling is a ...key challenge encountered by any implantable system. This is particularly an issue immediately after implantation, when the foreign body response and associated biofouling processes are at their most active in passivating a foreign object. Here, we present the development of a sensor protection and activation strategy against biofouling, based on coatings consisting of a pH-triggered, dissolvable polymer, that covered a functionalised electrode surface. We demonstrate that reproducible delayed sensor activation can be achieved, and that the length of this delay can be controlled by the optimisation of coating thickness, homogeneity and density through tuning of the coating method and temperature. Comparative evaluation of the polymer-coated and uncoated probe-modified electrodes in biological media revealed significant improvements in their anti-biofouling characteristics, demonstrating that this offers a promising approach to the design of enhanced sensing devices.
For analytical applications involving label-free biosensors and multiple measurements, i.e., across an electrode array, it is essential to develop complete sensor systems capable of functionalization ...and of producing highly consistent responses. To achieve this, a multi-microelectrode device bearing twenty-four equivalent 50 µm diameter Pt disc microelectrodes was designed in an integrated 3-electrode system configuration and then fabricated. Cyclic voltammetry and electrochemical impedance spectroscopy were used for initial electrochemical characterization of the individual working electrodes. These confirmed the expected consistency of performance with a high degree of measurement reproducibility for each microelectrode across the array. With the aim of assessing the potential for production of an enhanced multi-electrode sensor for biomedical use, the working electrodes were then functionalized with 6-mercapto-1-hexanol (MCH). This is a well-known and commonly employed surface modification process, which involves the same principles of thiol attachment chemistry and self-assembled monolayer (SAM) formation commonly employed in the functionalization of electrodes and the formation of biosensors. Following this SAM formation, the reproducibility of the observed electrochemical signal between electrodes was seen to decrease markedly, compromising the ability to achieve consistent analytical measurements from the sensor array following this relatively simple and well-established surface modification. To successfully and consistently functionalize the sensors, it was necessary to dilute the constituent molecules by a factor of ten thousand to support adequate SAM formation on microelectrodes. The use of this multi-electrode device therefore demonstrates in a high throughput manner irreproducibility in the SAM formation process at the higher concentration, even though these electrodes are apparently functionalized simultaneously in the same film formation environment, confirming that the often seen significant electrode-to-electrode variation in label-free SAM biosensing films formed under such conditions is not likely to be due to variation in film deposition conditions, but rather kinetically controlled variation in the SAM layer formation process at these microelectrodes.
Nuclear fission technologies have the potential to play a significant role in the energy mix of a net-zero and sustainable society. However, to achieve the sustainability goal two significant ...challenges remain: efficient and sustainable fuel usage and the minimization of long-term nuclear waste. Civil nuclear molten salt systems and technologies offer the opportunity to address both, delivering future reactors at scale for efficient and effective power production and nuclear waste burnup. Potentially, both objectives could be fulfilled in one reactor system, which could significantly improve sustainability indices. The key to this innovation is demand driven development of a significantly reduced fuel cycle with enhanced proliferation resistance which offers further potential for improvement. To achieve these goals, a transformative approach for salt clean-up during molten salt reactor operation is proposed, by concentrating on the detection and removal of key neutron poisoning elements which prevent the reactor from long-term operation. To enable this highly innovative development work, a novel analysis of the evolving elementary fuel composition, their concentrations, and their criticality influence is now provided in this work. This, combined with consideration of the oxidation states of each of these elements then provides the basis for the selection of these key poisons and the development of advanced separation processes and process monitoring. This work also discusses the importance of the effective integration of physics and chemistry when systems modelling in achieving these system development goals.
An MRSA assay requiring neither labeling nor amplification of target DNA has been developed. Sequence specific binding of fragments of bacterial genomic DNA is detected at femtomolar concentrations ...using electrochemical impedance spectroscopy (EIS). This has been achieved using systematic optimisation of probe chemistry (PNA self-assembled monolayer film on gold electrode), electrode film structure (the size and nature of the chemical spacer) and DNA fragmentation, as these are found to play an important role in assay performance. These sensitivity improvements allow the elimination of the PCR step and DNA labeling and facilitate the development of a simple and rapid point of care test for MRSA. Assay performance is then evaluated and specific direct detection of the MRSA diagnostic mecA gene from genomic DNA, extracted directly from bacteria without further treatment is demonstrated for bacteria spiked into saline (10(6) cells per mL) on gold macrodisc electrodes and into human wound fluid (10(4) cells per mL) on screen printed gold electrodes. The latter detection level is particularly relevant to clinical requirements and point of care testing where the general threshold for considering a wound to be infected is 10(5) cells per mL. By eliminating the PCR step typically employed in nucleic acid assays, using screen printed electrodes and achieving sequence specific discrimination under ambient conditions, the test is extremely simple to design and engineer. In combination with a time to result of a few minutes this means the assay is well placed for use in point of care testing.
The etiologies of meningitis range in severity from benign and self-limited to life-threatening with potentially severe morbidity. Bacterial meningitis is a medical emergency that requires prompt ...recognition and treatment. Mortality remains high despite the introduction of vaccinations for common pathogens that have reduced the incidence of meningitis worldwide. Aseptic meningitis is the most common form of meningitis with an annual incidence of 7.6 per 100,000 adults. Most cases of aseptic meningitis are viral and require supportive care. Viral meningitis is generally self-limited with a good prognosis. Examination maneuvers such as Kernig sign or Brudzinski sign may not be useful to differentiate bacterial from aseptic meningitis because of variable sensitivity and specificity. Because clinical findings are also unreliable, the diagnosis relies on the examination of cerebrospinal fluid obtained from lumbar puncture. Delayed initiation of antibiotics can worsen mortality. Treatment should be started promptly in cases where transfer, imaging, or lumbar puncture may slow a definitive diagnosis. Empiric antibiotics should be directed toward the most likely pathogens and should be adjusted by patient age and risk factors. Dexamethasone should be administered to children and adults with suspected bacterial meningitis before or at the time of initiation of antibiotics. Vaccination against the most common pathogens that cause bacterial meningitis is recommended. Chemoprophylaxis of close contacts is helpful in preventing additional infections.
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