A study of the dynamic behaviour of a pulsed column solvent extraction plant

A study has been made of the dynamic behaviour of a nuclear fuel reprocessing plant utilising pulsed solvent extraction columns. A flowsheet is presented and the choice of an extraction device is discussed. The plant is described by a series of modules each module representing an item of equipment. Each module consists of a series of differential equations describing the dynamic behaviour of the equipment. The model is written in PMSP, a language developed for dynamic simulation models. The differential equations are solved to predict plant behaviour with time. The dynamic response of the plant to a range of disturbances has been assessed. The interactions between pulsed columns have been demonstrated and illustrated. The importance of auxillary items of equipment to plant performance is demonstrated. Control of the reprocessing plant is considered and the effect of control parameters on performance assessed

The structure and possible origins of stacking faults in gamma-yttrium disilicate

Parallel stacking faults on (010) planes are frequently observed in hot-pressed Y2Si2O7. A combination of conventional dark-field imaging and high-resolution transmission electron microscopy was used to investigate the structure of these faults and it was found that they consist of the repeat of one layer of the two layer γ-Y2Si2O7 structure with an associated in-plane rigid body displacement. The resulting structure was confirmed by image simulation of high-resolution images from two perpendicular projections. A model for the formation of the stacking faults is proposed as a consequence of a transformation from β-Y2Si2O7 to γ-Y2Si2O7 in the hot pressing

Cell surface changes induced by vaccinia virus

Virus-specified antigens induced in the membranes of infected cells have been implicated as primary targets in the recognition and destruction of virus-infected cells by the immune system of mammalian hosts. Antigenic changes induced in the plasma membranes of vaccinia-infected HeLa cells 2 h post-infection were detected by immunofluorescence, immune haemadsorption, and to a lesser extent by complement-fixation and complement-mediated cytolysis. Cytopathic effects (cell rounding) were seen prior to viral DM replication and also when this was blocked. Other changes occurred at the cell surface later in infection when turkey erythrocytes and concanavalin A were bound by cells. There was no evidence for an overall increase in mucopolysaccharide synthesis in the form of sialic acid. Quantitative spectrophotometric assays for haemadsorption, immune haemadsorption and concanavalin A binding were developed and the effect of varying growth or reaction conditions on the expression of vaccinia haemagglutinin at the surface of infected cells was investigated. Vaccinia cell surface haemagglutinin (VHA), detected by the binding of turkey erythrocytes, was synthesised around 10 h post-infection, even under conditions of low multiplicity of infection, and was closely coincident with the appearance of infectious virus. Of seven different cell lines tested, haemadsorption was greatest in HeLa cells and least in L-929 cells. Other red cell species were bound to infected cells to a lesser degree than turkey cells. Haemadsorption occurred within the physiological and alkaline pH ranges and at temperatures between 2

Defining Fuel Poverty in Northern Ireland: A preliminary review

Measures to tackle fuel poverty in Northern Ireland over the past decade have been effective but much more needs to be done, new research carried out by the University of Ulster has revealed.‘Defining Fuel Poverty: A Preliminary Review’, which was commissioned by the Department of Social Development, was launched at the Stormont Hotel by the DSD Minister Nelson McCausland.Christine Liddell, Professor of Psychology at the University of Ulster, led the independent Preliminary Review of fuel poverty, which is one of three being carried out across the UK.She said: “While efforts to tackle fuel poverty in Northern Ireland have made measurable inroads – the severity of fuel poverty remains profound for many households.“The Preliminary Review concludes, based on the extensive evidence gathered, that past and present approaches to tackling fuel poverty in Northern Ireland have delivered a highly cost-effective programme of housing regeneration. Returns from investment in Warm Homes and similar programmes include:-       substantial impacts on human health and well-being;-       significant savings on energy bills for thousands of households;-       measurable returns in terms of job creation;-       a widening of opportunities for consolidating partnerships across the public and private sector

Purification of therapeutic & prophylactic mRNA by affinity chromatography

In vitro transcribed mRNA is an emerging therapeutic and prophylactic modality with the potential to transform medicine. The drug platform features exceptionally rapid development and versatility of manufacturing processes. Despite the prompt advancement of mRNA from trials to market, purification challenges remain. The cell-free synthesis of mRNA is responsible for the generation of product and process-related impurities, creating the potential for immunogenic effects and decreased translatability into the clinic. Affinity chromatography presents itself as an effective primary capture step for the isolation of functional transcripts from product and some process related impurities. Developing platform processes for the affinity purification of mRNA is hindered by the varying strand lengths of non-amplifying, self-amplifying, and trans-amplifying constructs, with disparities in capacity being observed. Ligand chemistries may contribute to non-specific binding events which remain challenging to characterise. Improved elution and wash conditions may be pursued through novel ligand chemistries, enhanced density and spacing. Regardless of the size or application of the product, the impurities generated by in vitro transcription represent a significant obstacle to the safe administration and long-term storage of mRNA. Affinity chromatography is a valuable tool in overcoming these challenges, with current commercially available products relying heavily on oligo deoxythymidine ligand chemistries. Whilst affinity chromatography is highly valuable in the purification of mRNA, the inability to separate key secondary structures such as double-stranded RNA means it remains to be seen if this technology will adopt the same position as protein A does in mAb manufacture

Carotenoporphyrins as selective photodiagnostic agents for tumours.

The covalent binding of a carotene moiety to one phenyl ring and meso-tetraphenyl-substituted porphyrins (see Figure 1) efficiently quenches the photosensitising activity of the porphyrin while a relatively large yield of fluorescence emission around 650 nm is retained. Pharmacokinetic studies performed with two carotenoporphyrins (CPs) and the corresponding porphyrins (Ps) in Balb/c mice bearing an MS-2 fibrosarcoma show that the two Ps give a high selectivity of tumour localisation (tumour/peritumoral tissue ratios of dye concentration ranging between c. 30 and 90 at 24 h after injection of 4.2-8.4 mumol kg-1 in a Cremophor emulsion) and photosensitive tumour necrosis upon red light irradiation. For the same injected doses, the two CPs show no tumour-photosensitising activity even though they localise in the tumour in concentrations of the order of 10-40 micrograms g-1 at 24 h with tumour/peritumoral ratios larger than 10. Thus, the fluorescence emitted by these CPs in the tumour can be used for photodiagnostic purposes with no risk of skin photosensitisation. However, this approach is presently limited by the large accumulation and prolonged retention of the CPs in the liver and spleen

Molecular determinants of a competent bovine corpus luteum: first vs final wave dominant follicles

Reproductive management in cattle requires the synchrony of follicle development and oestrus before insemination. However, ovulation of follicles that have not undergone normal physiological maturation can lead to suboptimal luteal function. Here, we investigated the expression of a targeted set of 47 genes in (a) a first-wave vs final-wave dominant follicle (DF; the latter destined to ovulate spontaneously) and (b) 6-day-old corpora lutea (CLs) following either spontaneous ovulation or induced ovulation of a first-wave DF to ascertain their functional significance for competent CL development. Both the mass and progesterone-synthesising capacity of a CL formed following induced ovulation of a first-wave DF were impaired. These impaired CLs had reduced expression of steroidogenic enzymes (e.g. STAR and HSD3B1), luteotrophic receptors (LHCGR) and angiogenic regulators (e.g. VEGFA) and increased expression of BMP2 (linked to luteolysis). Relative to final-wave DFs, characteristic features of first-wave DFs included reduced oestradiol concentrations and a reduced oestradiol:progesterone ratio in the face of increased expression of key steroidogenic enzymes (i.e. CYP11A1, HSD3B1 and CYP19A1) in granulosa cells and reduced expression of the HDL receptor SCARB1 in thecal cells. Transcripts for further components of the TGF and IGF systems (e.g. INHA, INHBA, IGF2R and IGFBP2) varied between the first- and final-wave DFs. These results highlight the importance of hormones such as progesterone interacting with local components of both the TGF and IGF systems to affect the maturation of the ovulatory follicle and functional competency of the subsequent CL

Course and predictors of posttraumatic stress and depression longitudinal symptom profiles in refugees:A latent transition model

Exposure to potentially traumatic events and post-migration living difficulties (PMLDs) may explain the high rates of posttraumatic stress disorder (PTSD) and depression in resettled refugees. Latent class analyses (LCAs) in refugees have identified subgroups that differ in symptom profiles of PTSD and comorbid symptoms. However, knowledge on longitudinal symptom profiles in refugees is sparse. Examining longitudinal PTSD and depression symptom profiles could provide information on risk factors underlying worsening of symptoms post-resettlement. Self-rated PTSD (Posttraumatic Diagnostic Scale) and depression (Patient Health Questionnaire-9) symptoms were assessed among 613 refugees who had resettled in Australia up to two years previously (W1) and at 6 months follow-up (W2). PTSD and depression symptom profiles were identified using LCAs for W1 and W2 separately. Latent transition analysis was used to examine (predictors of) changes in symptom profiles, including gender, age, trauma exposure, and PMLDs. Four classes were identified that were consistent across timepoints: a No symptoms (W1 61%; W2 68%), Low PTSD/Moderate depression (W1 16%; W2 10%), Moderate PTSD/depression (W1 16%; W2 14%), and High symptoms class (W1 7%; W2 7%). Higher levels of problems with PMLDs, including being discrimination and family separation, predicted movements out of the No symptom class at W1 to classes with psychopathology at W2. To conclude, most participants did not develop PTSD or depression symptoms. The risk of developing these symptoms seems higher when problems with interpersonal PMLDs increased, pointing to the need for considering these stressors when addressing the mental health needs in this population

Towards a Parasitic Ethics

The parasite is widely conceived as a negative figure that takes without giving; perceived as an agent of corruption and destruction, it is subjected to programmes of eradication and expulsion across cultural, economic, political and ethical contexts. This paper offers an alternative approach to the status of parasitic relations in light of Michel Serres’s The Parasite, elaborated through ethnographic research into the after-hours culture and hidden economy of London’s Borough Market. We highlight the mutual dependence of agents in host-parasite networks according to what we term ‘general parasitism’, while inquiring into its ethical potential. Ultimately, we argue that while taking into account the near ubiquity of parasitic relations cannot form the basis for any concrete axiomatic ethical paradigm, it should at least encourage an ethics of hesitation before judgement when faced with any apparent instance of parasitism: to presume that parasitism is undesirable and unethical is itself undesirable and unethical

Assessing the effects of a drought experiment on the reproductive phenology and ecophysiology of a wet tropical rainforest community

Climate change is expected to increase the intensity and occurrence of drought in tropical regions, potentially affecting the phenology and physiology of tree species. Phenological activity may respond to a drying and warming environment by advancing reproductive timing, and/or diminishing the production of flowers and fruits. These changes have the potential to disrupt important ecological processes, with potentially wide-ranging effects on tropical forest function. Here, we analysed the monthly flowering and fruiting phenology of a tree community (337 individuals from 30 species) over seven years in a lowland tropical rainforest in north-eastern Australia, and its response to a through fall exclusion drought experiment (TFE) that was carried out from 2016 to 2018 (three years), excluding approximately 30% of rainfall. We further examined the eco-physiological effects of the TFE on the elemental (C:N) and stable isotope (d13C and d15N) composition of leaves, and on the stable isotope composition (d13C and d18O) of stem wood of four tree species. At the community level, there was no detectable effect of the TFE on flowering activity overall but there was a significant effect recorded on fruiting and varying responses from the selected species. The reproductive phenology and physiology of the four species examined in detail were largely resistant to impacts of the TFE treatment. One canopy species in the TFE significantly increased in fruiting and flowering activity whereas one understory species decreased significantly in both. There was a significant interaction between the TFE treatment and season on leaf C:N for two species. Stable isotope responses were also variable among species, indicating species-specific responses to the TFE. Thus, we did not observe consistent patterns in physiological and phenological changes in the tree community within the three years of TFE treatment examined in this study