Development of masterbatches for poly (ethylene terephthalate) with improved resistance to CO2 permeation

This research has investigated nanocomposite based masterbatches as routes to improve the CO2 retention properties of PET bottles. Masterbatches of different types of polyamide/clay, PET/clay, PET/nano-silica flakes and PET/divalent layered metal phosphonates (DLMP) were produced by melt compounding and evaluated. In the case of polyamide based nanocomposites PA6 was found to produce the best dispersed nanocomposites followed by PA-MXD6, PA-6I/6T and PA-6-3-T. It was concluded from the results that surfactant/polymer compatibility and thermal stability play some role, but the most significant factor in effecting good dispersion was the polarity of the polymer and its ability to directly interact with the clay surface. The CO2 retention of PET/PA blends showed MXD6 to offer by far the greatest improvement (100% increase) but the use of PA-MXD6 nanocomposite did not result in further improvement. It was concluded that transfer of exfoliated clay platelets from the PA phase to the PET phase had not occurred. In order to address this issue and disperse the filler effectively through both polymer matrices several novel new processes were developed and the use of a catalyst was investigated. Overall, the novel PET/MXD6/clay blends had reduced CO2 retention compared to the direct PET/MXD6 blend due to significant degradation of the polymers in the extrusion stage prior to bottle manufacture. Nanocomposites produced by direct melt mixing of PET and organoclay were always intercalated in nature (with the exception of C30B and hexadecyl pyridinium surfactant where the layered structure collapsed due to degradation of the surfactant). A consistent interlayer spacing of ~3.15-3.25nm was observed for all these materials and it was concluded that a stable PET crystal structure had formed as the distance between layers corresponds to three repeats of the c dimension of the crystal unit cell. It is proposed that the stable equilibrium forms due to insufficient direct interaction between the polymer and the clay surface. Despite relatively poor dispersion modest improvements in CO2 barrier were achieved (up to 25%). The use of novel nano-silica flakes resulted in improved CO2 retention, particularly with the 100nm thickness grade (30% improvement) despite considerable breakage of the nano-silica flakes during melt compounding. In the case of DLMP the dispersion of the fillers was found to be poor and no improvement in CO2 barrier was obtained. It was also observed that all the fillers applied acted as nucleating agents for polymer crystallisation in the polymer systems to which they were applied

Persistent microglial activation and synaptic loss with behavioral abnormalities in mouse offspring exposed to CASPR2-antibodies in utero

Gestational transfer of maternal antibodies against fetal neuronal proteins may be relevant to some neurodevelopmental disorders, but until recently there were no proteins identified. We recently reported a fivefold increase in CASPR2-antibodies in mid-gestation sera from mothers of children with intellectual and motor disabilities. Here, we exposed mice in utero to purified IgG from patients with CASPR2-antibodies (CASPR2-IgGs) or from healthy controls (HC-IgGs). CASPR2-IgG but not HC-IgG bound to fetal brain parenchyma, from which CASPR2-antibodies could be eluted. CASPR2-IgG exposed neonates achieved milestones similarly to HC-IgG exposed controls but, when adult, the CASPR2-IgG exposed progeny showed marked social interaction deficits, abnormally located glutamatergic neurons in layers V-VI of the somatosensory cortex, a 16% increase in activated microglia, and a 15-52% decrease in glutamatergic synapses in layers of the prefrontal and somatosensory cortices. Thus, in utero exposure to CASPR2-antibodies led to permanent behavioral, cellular, and synaptic abnormalities. These findings support a pathogenic role for maternal antibodies in human neurodevelopmental conditions, and CASPR2 as a potential target

Expected Performance of the ATLAS Experiment - Detector, Trigger and Physics

A detailed study is presented of the expected performance of the ATLAS detector. The reconstruction of tracks, leptons, photons, missing energy and jets is investigated, together with the performance of b-tagging and the trigger. The physics potential for a variety of interesting physics processes, within the Standard Model and beyond, is examined. The study comprises a series of notes based on simulations of the detector and physics processes, with particular emphasis given to the data expected from the first years of operation of the LHC at CERN

Advanced paternal age effects in neurodevelopmental disorders?review of potential underlying mechanisms

Multiple epidemiological studies suggest a relationship between advanced paternal age (APA) at conception and adverse neurodevelopmental outcomes in offspring, particularly with regard to increased risk for autism and schizophrenia. Conclusive evidence about how age-related changes in paternal gametes, or age-independent behavioral traits affect neural development is still lacking. Recent evidence suggests that the origins of APA effects are likely to be multidimensional, involving both inherited predisposition and de novo events. Here we provide a review of the epidemiological and molecular findings to date. Focusing on the latter, we present the evidence for genetic and epigenetic mechanisms underpinning the association between late fatherhood and disorder in offspring. We also discuss the limitations of the APA literature. We propose that different hypotheses relating to the origins of the APA effects are not mutually exclusive. Instead, multiple mechanisms likely contribute, reflecting the etiological complexity of neurodevelopmental disorders

Do schistosome vaccine trials in mice have an intrinsic flaw that generates spurious protection data?

The laboratory mouse has been widely used to test the efficacy of schistosome vaccines and a long list of candidates has emerged from this work, many of them abundant internal proteins. These antigens do not have an additive effect when co-administered, or delivered as SWAP homogenate, a quarter of which comprises multiple candidates; the observed protection has an apparent ceiling of 40–50 %. We contend that the low level of maturation of penetrating cercariae (~32 % for Schistosoma mansoni) is a major limitation of the model since 68/100 parasites fail to mature in naïve mice due to natural causes. The pulmonary capillary bed is the obstacle encountered by schistosomula en route to the portal system. The fragility of pulmonary capillaries and their susceptibility to a cytokine-induced vascular leak syndrome have been documented. During lung transit schistosomula burst into the alveolar spaces, and possess only a limited capacity to re-enter tissues. The acquired immunity elicited by the radiation attenuated (RA) cercarial vaccine relies on a pulmonary inflammatory response, involving cytokines such as IFNγ and TNFα, to deflect additional parasites into the alveoli. A principal difference between antigen vaccine protocols and the RA vaccine is the short interval between the last antigen boost and cercarial challenge of mice (often two weeks). Thus, after antigen vaccination, challenge parasites will reach the lungs when both activated T cells and cytokine levels are maximal in the circulation. We propose that “protection” in this situation is the result of physiological effects on the pulmonary blood vessels, increasing the proportion of parasites that enter the alveoli. This hypothesis will explain why internal antigens, which are unlikely to interact with the immune response in a living schistosomulum, plus a variety of heterologous proteins, can reduce the level of maturation in a non-antigen-specific way. These proteins are “successful” precisely because they have not been selected for immunological silence. The same arguments apply to vaccine experiments with S. japonicum in the mouse model; this schistosome species seems a more robust parasite, even harder to eliminate by acquired immune responses. We propose a number of ways in which our conclusions may be tested

From staff-mix to skill-mix and beyond: towards a systemic approach to health workforce management

Throughout the world, countries are experiencing shortages of health care workers. Policy-makers and system managers have developed a range of methods and initiatives to optimise the available workforce and achieve the right number and mix of personnel needed to provide high-quality care. Our literature review found that such initiatives often focus more on staff types than on staff members' skills and the effective use of those skills. Our review describes evidence about the benefits and pitfalls of current approaches to human resources optimisation in health care. We conclude that in order to use human resources most effectively, health care organisations must consider a more systemic approach - one that accounts for factors beyond narrowly defined human resources management practices and includes organisational and institutional conditions