Correction: Synthesis and characterisation of brannerite compositions (U0.9Ce0.1)1-x M x Ti2O6 (M = Gd3+, Ca2+) for the immobilisation of MOX residues.

[This corrects the article DOI: 10.1039/C7RA11742F.].

Synthesis and characterization of iodovanadinite using PdI2, an iodine source for the immobilisation of radioiodine.

The synthesis of a palladium-containing iodovanadinite derivative, hypothetically "PdPb9(VO4)6I2", was attempted using PdI2 as a source of iodine in searching for a novel waste form for radioiodine. Stoichiometric amounts of Pb3(VO4)2 and PdI2 were batched and reacted at elevated temperatures in sealed vessels. Batched material was also subjected to high-energy ball-milling (HEBM) in order to reduce reaction time and the potential for iodine volatilization during subsequent reaction at 200-500 °C. The resulting products were characterized using X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray analysis, IR spectroscopy, thermal analysis and Pd K XANES. Results showed that PdI2 can function as a sacrificial iodine source for the formation of iodovanadinite, prototypically Pb10(VO4)6I2, however, the incorporation of Pd into this phase was not definitively observed. The sacrificial reaction mechanism involved the decomposition of PdI2 to Pd metal and nascent I2, with the latter incorporated into the iodovanadinite Pb10(VO4)6I2 phase. In comparison to processing using standard solid state reaction techniques, the use of HEBM prior to high temperature reaction generates a more homogeneous end-product with better iodine retention for this system. Overall, the key novelty and importance of this work is in demonstrating a method for direct immobilisation of undissolved PdI2 from nuclear fuel reprocessing, in a composite wasteform in which I-129 is immobilised within a durable iodovandinite ceramic, encapsulating Pd metal.

A synchrotron X-ray spectroscopy study of titanium co-ordination in explosive melt glass derived from the trinity nuclear test.

The speciation of Ti in trinitite, the explosive melt glass derived from the Trinity Test of 16th of July 1945, was investigated by X-ray absorption spectroscopy (XAS). Ti K-edge XANES showed that Ti was present in the Ti(iv) oxidation state for all samples. Fitting of pre-edge features by Gaussian functions and comparison with standards of known Ti coordination revealed significant variation in Ti coordination environment between samples. The variation of Ti coordination may be attributed to several factors including specific local chemistry and thermal histories of samples, in keeping with the highly heterogeneous microstructure of trinitite and the arkosic sand source material.

Synthesis and characterisation of brannerite compositions (U0.9Ce0.1)1-x M x Ti2O6 (M = Gd3+, Ca2+) for the immobilisation of MOX residues.

A suite of uranium brannerites for the disposal of MOX residues, formulated (U0.9Ce0.1)1-x M x Ti2O6 (M = Ca2+ and/or Gd3+), were prepared using a mixed oxide route under oxidising, inert and reducing atmospheres (air, argon and H2/N2). Gd3+ was added to act as a neutron absorber in the final Pu bearing wasteform and Ce added to function as a structural analogue for Pu. X-ray powder diffraction of the synthesised specimens found that phase distribution was strongly affected by the processing atmosphere and Gd content. In all cases prototypical brannerite was formed, accompanied by different secondary phases dependent on processing atmosphere. Microstructural analysis (SEM) of the sintered samples confirmed the results of the X-ray powder diffraction. Bulk XANES found that Ti remained in the Ti4+ oxidation state whereas Ce was uniformly reduced to the Ce3+ oxidation state regardless of processing conditions or stoichiometry. Micro-focus XANES was used to determine U oxidation in the brannerite phase and showed that U oxidised to higher U oxidation states to charge compensate. It was concluded that the charge balance mechanism was a combination of U oxidation and A-site vacancies.

Percolation-based risk index for pathogen invasion: application to soilborne disease in propagation systems.

Propagation systems for seedling growth play a major role in agriculture, and in notable cases (such as organic systems), are under constant threat from soil and seedborne fungal plant pathogens such as Rhizoctonia solani or Pythium spp. Yet, to date little is known that links the risk of disease invasion to the host density, which is an agronomic characteristic that can be readily controlled. We introduce here, for the first time in an agronomic system, a percolation framework to analyze the link. We set up an experiment to study the spread of the ubiquitous fungus R. solani in replicated propagation systems with different planting densities, and fit a percolation-based epidemiological model to the data using Bayesian inference methods. The estimated probability of pathogen transmission between infected and susceptible plants is used to calculate the risk of invasion. By comparing the transmission probability and the risk values obtained for different planting densities, we are able to give evidence of a nonlinear relationship between disease invasion and the inter-plant spacing, hence to demonstrate the existence of a spatial threshold for epidemic invasion. The implications and potential use of our methods for the evaluation of disease control strategies are discussed.

With a little help from my friends: androgens tap BDNF signaling pathways to alter neural circuits.

Gonadal androgens are critical for the development and maintenance of sexually dimorphic regions of the male nervous system, which is critical for male-specific behavior and physiological functioning. In rodents, the motoneurons of the spinal nucleus of the bulbocavernosus (SNB) provide a useful example of a neural system dependent on androgen. Unless rescued by perinatal androgens, the SNB motoneurons will undergo apoptotic cell death. In adulthood, SNB motoneurons remain dependent on androgen, as castration leads to somal atrophy and dendritic retraction. In a second vertebrate model, the zebra finch, androgens are critical for the development of several brain nuclei involved in song production in males. Androgen deprivation during a critical period during postnatal development disrupts song acquisition and dimorphic size-associated nuclei. Mechanisms by which androgens exert masculinizing effects in each model system remain elusive. Recent studies suggest that brain-derived neurotrophic factor (BDNF) may play a role in androgen-dependent masculinization and maintenance of both SNB motoneurons and song nuclei of birds. This review aims to summarize studies demonstrating that BDNF signaling via its tyrosine receptor kinase (TrkB) receptor may work cooperatively with androgens to maintain somal and dendritic morphology of SNB motoneurons. We further describe studies that suggest the cellular origin of BDNF is of particular importance in androgen-dependent regulation of SNB motoneurons. We review evidence that androgens and BDNF may synergistically influence song development and plasticity in bird species. Finally, we provide hypothetical models of mechanisms that may underlie androgen- and BDNF-dependent signaling pathways.

Periodicity in host availability does not account for evolutionary branching as observed in many plant pathogens: an application to Gaeumannomyces graminis var. tritici.

Periodicity in host availability is common in agricultural systems. Although it is known to have profound effects on plant pathogen abundance, the evolutionary consequences of periodicity for the pathogen population have not previously been analyzed. An epidemiological model incorporating periodic absence of the host crop is combined with the theory of adaptive dynamics to determine whether or not seasonality in host presence plays a role in the occurrence of evolutionary branching, leading to coexisting yet genetically distinct pathogen phenotypes. The study is motivated and illustrated by the specific example of take-all disease of wheat, caused by the pathogen Gaeumannomyces graminis var. tritici, for which two coexisting but genetically distinct types and a trade-off related to seasonality in host presence have been identified. Numerical simulations are used to show that a trade-off between the pathogen transmission rate and the survival of the pathogen between cropping seasons cannot account for the evolutionary branching observed in many pathogens. Model elaborations show that this conclusion holds for a broad range of putative mechanisms. Although the analysis is motivated and illustrated by the specific example of take-all of wheat, the results apply to a broad range of pathogens.

Epidemiological analysis of take-all decline in winter wheat.

Take-all dynamics within crops differing in cropping history (the number of previous consecutive wheat crops) were analyzed using an epidemiological model to determine the processes affected during take-all decline. The model includes terms for primary infection, secondary infection, inoculum decay, and root growth. The average rates of root production did not vary with cropping history. The force of primary infection increased from a low level in 1st wheat crops, to a maximum in 2nd to 4th wheat crops, and then to intermediate levels thereafter. The force of secondary infection was low but increased steadily during the season in first wheat crops, was delayed but rose and fell sharply in 2nd to 4th wheat crops, and for 5th and 7th wheat crops returned to similar dynamics as that for 1st wheat crops. Chemical seed treatment with silthiofam had no consistent effect on the take-all decline process. We conjecture that these results are consistent with (i) low levels of particulate inoculum prior to the first wheat crop leading to low levels of primary infection, low levels of secondary infection, and little disease suppression; (ii) net amplification of inoculum during the first wheat crop and intercrop period; (iii) increased levels of primary and secondary infection in subsequent crops, but higher levels of disease suppression; and (iv) an equilibrium between the pathogen and antagonist populations by the 5th wheat, reflected by lower overall rates of primary infection, secondary infection, disease suppression and hence, disease severity.

Reversed halo sign in lymphomatoid granulomatosis.

Lymphomatoid granulomatosis is a rare lymphoproliferative disorder which affects extranodal sites, most commonly lung. Radiologically, it typically presents with multiple nodular opacities that may wax and wane. The reversed halo sign has previously been reported in cryptogenic organizing pneumonia and more recently in South American blastomycosis. We describe a case of histologically proven lymphomatoid granulomatosis in a patient who presented initially with the more typical nodular opacities, which subsequently progressed into the reversed halo sign. To the best of our knowledge, this association has not been previously described.

A comparative study of the enantiomeric separation of labeled amino acids with cyclodextrins and mixed micelles in capillary electrophoresis.

Enantiomeric separations of fluorescently labeled amino acids are studied by capillary electrophoresis (CE) under a novel variety of experimental conditions. Three different labels are evaluated using two different additives: cyclodextrins (beta- and gamma-) and a dual surfactant system of sodium dodecyl sulfate and sodium taurodeoxycholate. Fluorescein-5-isothiocyanate is the best label to use in this cyclodextrin-based system, and dansyl chloride is the best label to use in this dual surfactant system. Possible limitations for separation of the enantiomers using the mixed micelle system include the fact that there is little interaction of the solute with the surfactants, the negative charge of the solute is limiting the separation window of the system, and the amount of the chiral phase available for partitioning is limited. The separations using cyclodextrins as a chiral selector show that the label affects migration order of the enantiomers, and the cyclodextrins are very effective in separating numerous enantiomers. Overall, cyclodextrins are the better buffer additive for CE use, and the dual surfactant systems, including sodium taurodeoxycholate, offer future promise.

An Epidemiological Analysis of the Role of Disease-Induced Root Growth in the Differential Response of Two Cultivars of Winter Wheat to Infection by Gaeumannomyces graminis var. tritici.

ABSTRACT Epidemiological modeling combined with parameter estimation of experimental data was used to examine differences in the contribution of disease-induced root production to the spread of take-all on plants of two representative yet contrasting cultivars of winter wheat, Ghengis and Savannah. A mechanistic model, including terms for primary infection, secondary infection, inoculum decay, and intrinsic and disease-induced root growth, was fitted to data describing changes in the numbers of infected and susceptible roots over time at a low or high density of inoculum. Disease progress curves were characterized by consecutive phases of primary and secondary infection. No differences in root growth were detected between cultivars in the absence of disease and root production continued for the duration of the experiment. However, significant differences in disease-induced root production were detected between Savannah and Genghis. In the presence of disease, root production for both cultivars was characterized by stimulation when few roots were infected and inhibition when many roots were infected. At low inoculum density, the transition from stimulation to inhibition occurred when an average of 5.0 and 9.0 roots were infected for Genghis and Savannah, respectively. At high inoculum density, the transition from stimulation to inhibition occurred when an average of 4.5 and 6.7 roots were infected for Genghis and Savannah, respectively. Differences in the rates of primary and secondary infection between Savannah and Genghis also were detected. At a low inoculum density, Genghis was marginally more resistant to secondary infection whereas, at a high density of inoculum, Savannah was marginally more resistant to primary infection. The combined effects of differences in disease-induced root growth and differences in the rates of primary and secondary infection meant that the period of stimulated root production was extended by 7 and 15 days for Savannah at a low and high inoculum density, respectively. The contribution of this form of epidemiological modeling to the better management of take-all is discussed.

Epidemiology and chemical control of take-all on seminal and adventitious roots of wheat.

ABSTRACT Epidemiological modeling is used to examine the effect of silthiofam seed treatment on field epidemics of take-all in winter wheat. A simple compartmental model, including terms for primary infection, secondary infection, root production, and decay of inoculum, was fitted to data describing change in the number of diseased and susceptible roots per plant over thermal time obtained from replicated field trials. This produced a composite curve describing change in the proportion of diseased roots over time that increased monotonically to an initial plateau and then increased exponentially thereafter. The shape of this curve was consistent with consecutive phases of primary and secondary infection. The seed treatment reduced the proportion of diseased roots throughout both phases of the epidemic. However, analysis with the model detected a significant reduction in the rate of primary, but not secondary, infection. The potential for silthiofam to affect secondary infection from diseased seminal or adventitious roots was examined in further detail by extending the compartmental model and fitting to change in the number of diseased and susceptible seminal or adventitious roots. Rates of secondary infection from either source of infected roots were not affected. Seed treatment controlled primary infection of seminal roots from particulate inoculum but not secondary infection from either seminal or adventitious roots. The reduction in disease for silthiofam-treated plants observed following the secondary infection phase of the epidemic was not due to long-term activity of the chemical but to the manifestation of disease control early in the epidemic.

Epidemiological dynamics and the efficiency of biological control of soil-borne disease during consecutive epidemics in a controlled environment.

• A combination of experimentation and modelling is used to examine the role of epidemiological dynamics on the production and infectivity of inoculum and the efficiency of biocontrol by Trichoderma viride during consecutive epidemics of damping-off disease caused by the pathogen Rhizoctonia solani in crops of radish. • Changes in the net infectivity of inoculum at the beginning of first and second crops caused a switch in epidemiological dynamics. Epidemics of first crops were dominated by secondary infection leading to amplification of inoculum so that epidemics of second crops were overwhelmingly determined by primary infection. • The biocontrol agent reduced primary infection and hence parasitic amplification of inoculum in both first and second crops but the efficiency of control dropped from 91.7% in first crops to 64.8% in second crops, with sudden outbreaks of disease in second crops which had previously been disease-free. • We conclude that parasitic amplification can cause a rapid build-up of disease and inoculum over consecutive crops, leading to loss in the efficiency of biocontrol. This form of inoculum production is supplemented by saprotrophic infestation which can result in sudden outbreaks of disease in protected crops where control of disease had previously been fully successful.

Modeling and analysis of disease-induced host growth in the epidemiology of take-all.

ABSTRACT Epidemiological modeling, together with parameter estimation to experimental data, was used to examine the contribution of disease-induced root growth to the spread of take-all in wheat. Production of roots from plants grown in the absence of disease was compared with production of those grown in the presence of disease and the precise form of diseaseinduced growth was examined by fitting a mechanistic model to data describing change in the number of infected and susceptible roots over time from a low and a high density of inoculum. During the early phase of the epidemic, diseased plants produced more roots than their noninfected counterparts. However, as the epidemic progressed, the rate of root production for infected plants slowed so that by the end of the epidemic, and depending on inoculum density, infected plants had fewer roots than uninfected plants. The dynamical change in the numbers of infected and susceptible roots over time could only be explained by the mechanistic model when allowance was made for disease-induced root growth. Analysis of the effect of disease-induced root production on the spread of disease using the model suggests that additional roots produced early in the epidemic serve only to reduce the proportion of diseased roots. However, as the epidemic switches from primary to secondary infection, these roots perform an active role in the transmission of disease. Some consequence of disease-induced root growth for field epidemics is discussed.

Linear solvation energy relationships of mixed micelles of sodium dodecyl sulfate and decanol: towards a better model of octanol/water partitioning.

We show that we can alter the mechanism of micelle/water partitioning by the addition of decanol as a co-surfactant to an SDS micellar solution. Linear solvation energy relationship (LSER) studies indicate that as we increase the amount of decanol added to sodium dodecyl sulfate solution, the hydrogen bond donating ability of the aqueous phase increases and the cavity term of the micellar phase increases. We obtain a better correlation with octanol/water partitioning using the mixed micelle system compared to normal micelle solution. Choosing the appropriate micelle marker is very important. Significant changes in the LSER equations can occur if a different compound is used as the micelle marker.

pH effects on micelle-water partitioning determined by micellar electrokinetic chromatography.

In many biological and environmental situations, the pH of aqueous media varies and differences in solute partitioning may result. However, the majority of biopartitioning and hydrophobicity studies conducted have been at pH 7. Using migration factors measured by micellar electrokinetic chromatography, we have determined pH effects on micelle-water partitioning for 19 compounds. We develop an improvement to the migration factor equation and the corrected migration factor for aniline shows a definite increase as pH decreases. The corrected migration factor was constant for the rest of the compounds over the pH ranged studied. We also investigated five micelle markers and determined that decanophenone is the best micelle marker to date. Decanophenone has a strong chromophore, detectable at all pH levels, and is easy to dissolve in the mobile phase.

Adenovector-mediated gene delivery of interleukin-2 in metastatic breast cancer and melanoma: results of a phase 1 clinical trial.

We conducted a phase 1 trial of direct injection of an E1, E3-deleted adenovirus encoding interleukin-2 (AdCAIL-2) into subcutaneous deposits of melanoma or breast cancer. Twenty-three patients were injected at seven dose levels (10(7)-10(10) p.f.u). Local inflammation was observed at the site of injection in 60% of patients, but side-effects were otherwise minor. Incomplete local tumor regression occurred at the site of injection in 24% of patients, but no conventional clinical responses were seen. Circulating CD4 and CD8 counts fell significantly 24 h after injection. Post-injection biopsies demonstrated tumor necrosis and lymphocytic infiltration with the predominant tumor-infiltrating cells both CD3- and CD8-positive. Vector-derived sequences were detected in 14 of 18 biopsies examined 7 days after injection and vector-derived hIL-2 mRNA was detected in 80% of 7-day biopsies processed after injection of 10(8) p.f.u. of AdCAIL-2 or higher. While IL-2 was detectable by ELISA in tumor biopsies at 48 h, no protein was detectable in injected tumors after 7 days and no circulating IL-2 was detectable at any time-point. No Ad5E1 sequences were detected either before or after injection indicating absence of replication-competent virus or endogenous E1-like sequence; furthermore, only rare vector shedding was detected. Anti-adenovirus and neutralizing antibody titers were elevated 1 month after injection in all patients. This trial therefore confirms the safety of use of adenoviral vectors for gene delivery in humans and demonstrates successful transgene expression even in the face of pre-existing immunity to adenovirus.

Acquisition of fear conditioning in rats requires the synthesis of mRNA in the amygdala.

In this study, the role of mRNA synthesis in the amygdala was studied during the acquisition of conditional fear. Rats with cannulas placed in the basolateral region of the amygdala were trained with a series of noise-shock pairings in a distinctive observation chamber. One half of the rats were pretreated with the mRNA synthesis inhibitor actinomycin-D (act-D). Responding to the training context and the auditory stimulus in a novel context measured by defensive freezing was assessed. Pretreatment with act-D significantly attenuated fear responses to both stimuli. Animals receiving act-D injections exhibited normal reactions to the conditioned stimulus-unconditioned stimulus pairings in the initial training session and displayed normal learning when retrained 7 days after injections. These results indicate that the transcription of new mRNA and subsequent protein synthesis in the amygdala may be essential for neural plasticity during this form of associative learning.

Dynamics of primary and secondary infection in take-all epidemics.

ABSTRACT Using a combination of experimentation and mathematical modeling, the effects of initial (particulate) inoculum density on the dynamics of disease resulting from primary and secondary infection of wheat by the take-all fungus, Gaeumannomyces graminis var. tritici, were tested. A relatively high inoculum density generated a disease progress curve that rose monotonically toward an asymptote. Reducing the initial inoculum density resulted in a curve that initially was monotonic, rising to a plateau, but which increased sigmoidally to an asymptotic level of disease thereafter. Changes in the infectivity of particulate inoculum over time were examined in a separate experiment. Using a model that incorporated terms for primary and secondary infection, inoculum decay, and host growth, we showed that both disease progress curves were consistent with consecutive phases dominated, respectively, by primary and secondary infection. We examined the spread of disease from a low particulate inoculum density on seminal and adventitious root systems separately. Although seminal roots were affected by consecutive phases of primary and secondary infection, adventitious roots were affected only by secondary infection. We showed that the characteristic features of disease progress in controlled experiments were consistent with field data from crops of winter wheat. We concluded that there is an initial phase of primary infection by G. graminis var. tritici on winter wheat as seminal roots grow through the soil and encounter inoculum, but the rate of primary infection slows progressively as inoculum decays. After the initial phase, there is an acceleration in the rate of secondary infection on both seminal and adventitious roots that is stimulated by the increase in the availability of infected tissue as a source of inoculum and the availability of susceptible tissue for infection.