Multiobjective genetic algorithm strategies for electricity production from generation IV nuclear technology

Development of a technico-economic optimization strategy of cogeneration systems of electricity/hydrogen, consists in finding an optimal efficiency of the generating cycle and heat delivery system, maximizing the energy production and minimizing the production costs. The first part of the paper is related to the development of a multiobjective optimization library (MULTIGEN) to tackle all types of problems arising from cogeneration. After a literature review for identifying the most efficient methods, the MULTIGEN library is described, and the innovative points are listed. A new stopping criterion, based on the stagnation of the Pareto front, may lead to significant decrease of computational times, particularly in the case of problems involving only integer variables. Two practical examples are presented in the last section. The former is devoted to a bicriteria optimization of both exergy destruction and total cost of the plant, for a generating cycle coupled with a Very High Temperature Reactor (VHTR). The second example consists in designing the heat exchanger of the generating turbomachine. Three criteria are optimized: the exchange surface, the exergy destruction and the number of exchange modules

Optimization of electricity / hydrogen cogeneration from generation IV nuclear energy systems

One of the great motivations of studying and developing Generation IV (Gen IV) reactors of VHTR (Very High Temperature Reactor) design concept is their capacity to efficiently produce both electricity and H2 (hydrogen). This study aims at developing an optimization methodology for cogeneration systems of H2 and electricity, from Gen IV nuclear reactors, with respect to energy constraints, economics and conjuncture in term of demand. It lies within a scope of a collaboration between the Laboratoire de Génie Chimique (Toulouse, France) and the Commissariat à l’Energie Atomique (CEA, Cadarache, France) in order to compare various cogeneration systems from both energy and economics viewpoint. This paper presents the results of an optimization study based on the “minimal destruction of exergy” or “exergy loss” concept. This criterion, used within the framework of a mono-objective genetic algorithm optimizer, was applied successfully to electric and heat production from Gen IV systems

Inducible expression of beta defensins by human respiratory epithelial cells exposed to Aspergillus fumigatus organisms

<p>Abstract</p> <p>Background</p> <p><it>Aspergillus fumigatus</it>, a saprophytic mould, is responsible for life-threatening, invasive pulmonary diseases in immunocompromised hosts. The role of the airway epithelium involves a complex interaction with the inhaled pathogen. Antimicrobial peptides with direct antifungal and chemotactic activities may boost antifungal immune response.</p> <p>Results</p> <p>The inducible expression of defensins by human bronchial epithelial 16HBE cells and A549 pneumocyte cells exposed to <it>A. fumigatus </it>was investigated. Using RT-PCR and real time PCR, we showed an activation of hBD2 and hBD9 defensin genes: the expression was higher in cells exposed to swollen conidia (SC), compared to resting conidia (RC) or hyphal fragments (HF). The kinetics of defensin expression was different for each one, evoking a putative distinct function for each investigated defensin. The decrease of defensin expression in the presence of heat-inactivated serum indicated a possible link between defensins and the proteins of the host complement system. The presence of defensin peptide hBD2 was revealed using immunofluorescence that showed a punctual cytoplasmic and perinuclear staining. Quantification of the cells stained with anti hBD2 antibody demonstrated that SC induced a greater number of cells that synthesized hBD2, compared to RC or HF. Labelling of the cells with anti-hBD-2 antibody showed a positive immunofluorescence signal around RC or SC in contrast to HF. This suggests co-localisation of hBD2 and digested conidia. The HBD2 level was highest in the supernatants of cells exposed to SC, as was determined by sandwich ELISA. Experiments using neutralising anti-interleukine-1β antibody reflect the autocrine mechanism of defensin expression induced by SC. Investigation of defensin expression at transcriptional and post-transcriptional levels demonstrated the requirement of transcription as well as new protein synthesis during <it>A. fumigatus </it>defensin induction. Finally, induced defensin expression in primary culture of human respiratory cells exposed to <it>A. fumigatus </it>points to the biological significance of described phenomena.</p> <p>Conclusion</p> <p>Our findings provide evidence that respiratory epithelium might play an important role in the immune response during <it>Aspergillus </it>infection. Understanding the mechanisms of regulation of defensin expression may thus lead to new approaches that could enhance expression of antimicrobial peptides for potential therapeutic use during aspergillosis treatment.</p

Does 18F-Fluorocholine PET/CT add value to positive parathyroid scintigraphy in the presurgical assessment of primary hyperparathyroidism?

IntroductionTo investigate the value of presurgical 18F-FCH PET/CT in detecting additional hyperfunctioning parathyroids despite a positive 99mTc-sestamibi parathyroid scintigraphy in patients with primary hyperparathyroidism (pHPT).MethodsThis is a retrospective study involving patients with pHPT, positive parathyroid scintigraphy performed before 18F-FCH PET/CT, and parathyroid surgery achieved after PET/CT. Imaging procedures were performed according to the EANM practice guidelines. Images were qualitatively interpreted as positive or negative. The number of pathological findings, their topography, and ectopic location were recorded. Histopathology, Miami criterion, and biological follow-up were considered to ensure effective parathyroidectomy confirming the complete excision of all hyperfunctioning glands. The impact of 18F-FCH PET/CT on therapeutic strategy was recorded.Results64/632 scanned pHPT patients (10%) were included in the analysis. According to a per lesion-based analysis, sensitivity, specificity, positive predictive value, and negative predictive value of 99mTc-sestamibi scintigraphy were 82, 95, 87, and 93%, respectively. The same values for 18F-FCH PET/CT were 93, 99, 99, and 97%, respectively. 18F-FCH PET/CT showed a significantly higher global accuracy than 99mTc-sestamibi scintigraphy: 98% (CI: 95–99) vs. 91% (CI: 87–94%). Youden Index was 0.79 and 0.92 for 99mTc-sestamibi scintigraphy and 18F-FCH PET/CT, respectively. Scintigraphy and PET/CT were discordant in 13/64 (20%) patients (49 glands). 18F-FCH PET/CT identified nine pathologic parathyroids not detected by 99mTc-sestamibi scintigraphy in 8 patients (12.5%). Moreover, 18F-FCH PET/CT allowed the reconsideration of false-positive scintigraphic diagnosis (scinti+/PET-) for 8 parathyroids in 7 patients (11%). The 18F-FCH PET/CT influenced the surgical strategy in 7 cases (11% of the study population).ConclusionIn a preoperative setting, 18F-FCH PET/CT seems more accurate and useful than 99mTc-sestamibi scan in pHPT patients with positive scintigraphic results. Positive parathyroid scintigraphy could be not satisfactory before neck surgery particularly in patients with multiglandular disease, suggesting a need to evolve the practice and define new preoperative imaging algorithms including 18F-FCH PET/CT at the fore-front in pHPT patients

Influence des acquisitions dynamiques pelviennes sur l’interprétation des TEP-TDM à la 18F-Fluorocholine chez les patients avec adénocarcinome prostatique

Médecine nucléaireLe protocole d’acquisition TEP-TDM à la 18F-fluorocholine ne fait à l’heure actuelle pas l’objet d’un consensus clair chez les patients avec adénocarcinome prostatique. Nous proposons une évaluation de l’influence des acquisitions précoces sur l’interprétation finale de 221 examens (201 patients) réalisés entre janvier 2018 et septembre 2019 et analysés rétrospectivement par deux médecins nucléaires (un senior et un interne) sur cinq groupes de patients distingués selon leurs traitements antérieurs : prostatectomie totale (PT) sans radiothérapie pelvienne (RT) [groupe 1], RT sans PT [groupe 2], PT + RT [groupe 3], bilan d’extension initial [groupe 4], autres [groupe 5]. L’analyse a été réalisée en fonction de trois localisations d’intérêt : la loge prostatique, les ganglions pelviens et la trame osseuse pelvienne. L’évaluation reposait sur une échelle à 3 grades : forte présomption de foyer néoplasique [1], interprétation équivoque [2], faible présomption de foyer néoplasique [3]. La réalisation d’une phase dynamique pelvienne modifie l’interprétation de l’examen TEP-TDM à la 18F-fluorocholine dans environ 9% des cas, et ce résultat semble dépendant du niveau d’expertise du médecin nucléaire. Une modification significative de l’approche thérapeutique est susceptible d’avoir lieu en connaissance des données de la phase précoce sur un très faible effectif de patients (5/201). De plus, un nombre non négligeable de foyers pelviens restent d’interprétation litigieuse, même avec un protocole biphasique. Le profil thérapeutique des patients avant TEP n’a pas d’influence démontrée sur la variabilité de l’interprétation. Le bénéfice réel en routine clinique de la première acquisition apparaît donc faible, notamment au regard du temps machine utilisé. La durée d’examen pourrait également être réduite par la suppression de l’acquisition céphalique qui n’apporte pas d’élément supplémentaire susceptible de modifier la prise en charge du cancer de la prostate.At this time, there is little consensus regarding 18F-Fluorocholine PET/CT acquisition protocol in patients with prostatic adenocarcinoma. We therefore propose to assess the influence of early acquisition on final interpretation of 221 exams (201 patients) performed between January 2018 and September 2019, retrospectively analysed by two nuclear medicine physicians (one senior and one resident). Five groups of patients were distinguished in relation to their previous therapeutic strategies: radical prostatectomy (RP) without pelvic radiotherapy (RT) [group 1], RT without RP [group 2], RP + RT [group 3], first work-up for extension [group 4], others [group 5]. Our analysis focused on three specific anatomic sites: prostatic bed, pelvic nodes and pelvic bone. A three-grade scale was used for evaluation: high suspicion of tumor foci [1], equivocal interpretation [2], low suspicion of tumor foci [3]. Dynamic pelvic acquisition modifies 18F-Fluorocholine PET/CT interpretation in about 9% of total exams, and this result seems correlated with nuclear medicine physician’s own level of expertise. A significant change of therapeutic strategy is likely to occur only in a relatively few patients (5/201) when early acquisition is available. Moreover, even with a dual-phase protocol, many pelvic foci remain of ambiguous interpretation. Previous curative treatments (RP and/or RT) failed to demonstrate any influence on interpretation variability. There seems to be little routine benefit of early dynamic acquisition, especially given the substantial machine-time required. PET/CT duration time could also be reduced with the suppression of cephalic acquisition which does not provide any relevant information regarding prostate cancer management

Exergy analysis for Generation IV nuclear plant optimization

This article deals to the application of exergy concept to the energy production system involving a VHTR (Very High Temperature Reactor) coupled with an innovative electricity-generating cycle. The objective is to propose a general formulation to quantify the exergy destruction of the involved process components embedded in a thermodynamic simulator CYCLOP (Haubensack, 2004). The exergy destruction is thus identified as a major criterion to minimize. For this purpose, a genetic algorithm embedded in the so-called MULTIGEN environment is used. Finally, the optimization criterion, based on exergy destruction minimization, is applied to electrical production by a Brayton-Rankine combined cycle connected to a nuclear reactor. Some typical results are presented. The perspectives of this work including the cogeneration of hydrogen and electricity are highlighte

64^{64}CuCl2_2 PET Imaging of 4T1-Related Allograft of Triple-Negative Breast Cancer in Mice

International audience64CuCl2 is an economic radiotracer for oncologic PET investigations. In the present study, we characterized the uptake of 64CuCl2 in vivo by µPET/CT in an allograft 4T1-related mouse model (BALB/c) of advanced breast cancer. 18F-FDG was used as a comparator. Twenty-two animals were imaged 7–9 days following 4T1-cell implantation inside mammary glands. Dynamic 64CuCl2 µPET/CT acquisition or iterative static images up to 8 h p.i. were performed. Animal biodistribution and tumor uptake were first evaluated in vivo by µPET analysis and then assessed on tissue specimens. Concerning 18F-FDG µPET, a static acquisition was performed at 15 min and 60 min p.i. Tumor 64CuCl2 accumulation increased from 5 min to 4 h p.i., reaching a maximum value of 5.0 ± 0.20 %ID/g. Liver, brain, and muscle 64CuCl2 accumulation was stable over time. The tumor-to-muscle ratio remained stable from 1 to 8 h p.i., ranging from 3.0 to 3.7. Ex vivo data were consistent with in vivo estimations. The 18F-FDG tumor accumulation was 8.82 ± 1.03 %ID/g, and the tumor-to-muscle ratio was 4.54 ± 1.11. 64CuCl2 PET/CT provides good characterization of the 4T1-related breast cancer model and allows for exploration of non-glycolytic cellular pathways potentially of interest for theragnostic strategies

Radial viscous fingering in miscible Hele-Shaw flows: A numerical study

A modified version of the usual viscous fingering problem in a radial Hele-Shaw cell with immiscible fluids is studied by intensive numerical simulations. We consider the situation in which the fluids involved are miscible, so that the diffusing interface separating them can be driven unstable through the injection or suction of the inner fluid. The system is allowed to rotate in such a way that centrifugal and Coriolis forces come into play, imposing important changes on the morphology of the arising patterns. In order to bridge from miscible to immiscible pattern forming structures, we add the surface tensionlike effects due to Korteweg stresses. Our numerical experiments reveal a variety of interesting fingering behaviors, which depend on the interplay between injection (or suction), diffusive, rotational, and Korteweg stress effects. Whenever possible the features of the simulated miscible fronts are contrasted to existing experiments and other theoretical or numerical studies, usually resulting in close agreements. A number of additional complex morphologies, whose experimental realization is still not available, are predicted and discussed. © 2008 The American Physical Society