144 research outputs found

    The supramolecular chemistry of benzene- and pyridinepolycarboxylic acids

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    The term ‘supramolecular chemistry’ was defined by Lehn as ‘chemistry beyond the molecule’, the aggregation of molecular or ionic entities to yield extensive arrays. Supramolecular chemistry is essentially the designed chemistry of the intermolecular bond, encircling the traditionally distinct disciplines of organic, inorganic and physical chemistry. Metal-organic frameworks have been shown to facilitate selective gas sorption and selective binding of guest solvent molecules, with notable examples from the work of Yaghi et al. created from the coordination of benzenepolycarboxylates to metal centres. Authors including Herbstein have investigated the inclusion of solvent molecules in the solid-state structure of trimesic acid, preventing the interpenetration of this compound. Here, novel solvent inclusion compounds of hemimellitic acid, the 1,2,3-trisubstituted relative of trimesic acid, are presented in which the hydrogen bonded host network forms cavities in which solvent molecules reside. [Continues.

    Technology Challenges of SURROUND: A Constellation of Small Satellites Around the Sun for Tracking Solar Radio Bursts

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    The SURROUND mission proposes the operational monitoring and forecasting of space weather events using a constellation of five small satellites in orbit around the Sun. This unique mission concept would enable the localisation and tracking of solar events with unprecedented accuracy. The small payload combined with high launch requirements makes this an ideal candidate mission for a distributed constellation of small spacecraft and provides an opportunity for technical development in the areas of deep space communication, propulsion, and survivability. The baseline configuration for SURROUND proposes the deployment of spacecraft to Earth-Sun Lagrange points L1, L4, and L5, and two additional spacecraft in Earth leading (\u3c 1AU) and trailing (\u3e 1AU) orbits. However, the development and realisation of such a constellation in deep space presents a number of challenges, particularly when the use of small spacecraft is considered. This paper presents the conceptual design for the proposed SURROUND constellation, principally focusing on the key technical challenges of deploying the spacecraft into their desired locations around the Sun and subsequently communicating the collected data back to Earth. In addition to the key propulsion system and communications architecture trades, additional technological challenges of the mission are also considered, including attitude control, radiation hardening, and electromagnetic compatibility

    Genetic Diversity and Population Structure of the Secondary Symbiont of Tsetse Flies, Sodalis glossinidius, in Sleeping Sickness Foci in Cameroon

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    Human African trypanosomiasis remains a threat to the poorest people in Africa. The trypanosomes causing the disease are transmitted by tsetse flies. The drugs currently used are unsatisfactory: some are toxic and all are difficult to administer. Furthermore, drug resistance is increasing. Therefore, investigations for novel disease control strategies are urgently needed. Previous analyses showed the association between the presence of Glossina symbiont, Sodalis glossinidius, and the fly infection by trypanosomes in a south-western region in Cameroon: flies harbouring symbionts had a threefold higher probability of being infected by trypanosomes than flies devoid of symbionts. But the study also showed substantial differences in S. glossinidius and trypanosome infection rates between Glossina populations from two Cameroonian foci of sleeping sickness. We hypothesized that the geographical isolation of the two foci may have induced the independent evolution of each one, leading to the diversification of symbiont genotypes. Microsatellite markers were used and showed that genetic diversity structuring of S. glossinidius varies at different geographical scales with a low but significant differentiation between the Campo and Bipindi HAT foci. This encourages further work on interactions between S. glossinidius subpopulations and Glossina species that could favor tsetse fly infections by a given trypanosome species

    Linkage disequilibrium pattern of the ATM gene in breast cancer patients and controls; association of SNPs and haplotypes to radio-sensitivity and post-lumpectomy local recurrence

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    <p>Abstract</p> <p>Background</p> <p>The ATM protein is activated as a result of ionizing radiation, and genetic variants of the <it>ATM </it>gene may therefore affect the level of radiation-induced damage. Individuals heterozygous for <it>ATM </it>mutations have been reported to have an increased risk of malignancy, especially breast cancer.</p> <p>Materials and methods</p> <p>Norwegian breast cancer patients (272) treated with radiation (252 of which were evaluated for radiation-induced adverse side effects), 95 Norwegian women with no known history of cancer and 95 American breast cancer patients treated with radiation (44 of which developed ipsilateral breast tumour recurrence, IBTR) were screened for sequence variations in all exons of the <it>ATM </it>gene as well as known intronic variants by denaturating high performance liquid chromatography (dHPLC) followed by sequencing to determine the nature of the variant.</p> <p>Results and Conclusion</p> <p>A total of 56 variants were identified in the three materials combined. A borderline significant association with breast cancer risk was found for the 1229 T>C (Val>Ala) substitution in exon 11 (P-value 0.055) between the Norwegian controls and breast cancer patients as well as a borderline significant difference in haplotype distribution (P-value 0.06). Adverse side effects, such as: development of costal fractures and telangiectasias, subcutaneous and lung fibrosis, pleural thickening and atrophy were evaluated in the Norwegian patients. Significant associations were found for several of the identified variants such as rs1800058 (Leu > Phe) where a decrease in minor allele frequency was found with increasing level of adverse side effects for the clinical end-points pleural thickening and lung fibrosis, thus giving a protective effect. Overall our results indicate a role for variation in the <it>ATM </it>gene both for risk of developing breast cancer, and in radiation induced adverse side effects. No association could be found between risk of developing ipsilateral breast tumour recurrence and any of the sequence variants found in the American patient material.</p

    How to Exploit the Digitalization Potential of Business Processes

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    Process improvement is the most value-adding activity in the business process management (BPM) lifecycle. Despite mature knowledge, many approaches have been criticized to lack guidance on how to put process improvement into practice. Given the variety of emerging digital technologies, organizations not only face a process improvement black box, but also high uncertainty regarding digital technologies. This paper thus proposes a method that supports organizations in exploiting the digitalization potential of their business processes. To achieve this, action design research and situational method engineering were adopted. Two design cycles involving practitioners (i.e., managers and BPM experts) and end-users (i.e., process owners and participants) were conducted. In the first cycle, the method’s alpha version was evaluated by interviewing practitioners from five organizations. In the second cycle, the beta version was evaluated via real-world case studies. In this paper, detailed results of one case study, which was conducted at a semiconductor manufacturer, are included

    Bioenergetic status modulates motor neuron vulnerability and pathogenesis in a zebrafish model of spinal muscular atrophy

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    Degeneration and loss of lower motor neurons is the major pathological hallmark of spinal muscular atrophy (SMA), resulting from low levels of ubiquitously-expressed survival motor neuron (SMN) protein. One remarkable, yet unresolved, feature of SMA is that not all motor neurons are equally affected, with some populations displaying a robust resistance to the disease. Here, we demonstrate that selective vulnerability of distinct motor neuron pools arises from fundamental modifications to their basal molecular profiles. Comparative gene expression profiling of motor neurons innervating the extensor digitorum longus (disease-resistant), gastrocnemius (intermediate vulnerability), and tibialis anterior (vulnerable) muscles in mice revealed that disease susceptibility correlates strongly with a modified bioenergetic profile. Targeting of identified bioenergetic pathways by enhancing mitochondrial biogenesis rescued motor axon defects in SMA zebrafish. Moreover, targeting of a single bioenergetic protein, phosphoglycerate kinase 1 (Pgk1), was found to modulate motor neuron vulnerability in vivo. Knockdown of pgk1 alone was sufficient to partially mimic the SMA phenotype in wild-type zebrafish. Conversely, Pgk1 overexpression, or treatment with terazosin (an FDA-approved small molecule that binds and activates Pgk1), rescued motor axon phenotypes in SMA zebrafish. We conclude that global bioenergetics pathways can be therapeutically manipulated to ameliorate SMA motor neuron phenotypes in vivo

    Genome-wide Association Analysis in Humans Links Nucleotide Metabolism to Leukocyte Telomere Length

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    Leukocyte telomere length (LTL) is a heritable biomarker of genomic aging. In this study, we perform a genome-wide meta-analysis of LTL by pooling densely genotyped and imputed association results across large-scale European-descent studies including up to 78,592 individuals. We identify 49 genomic regions at a false dicovery rate (FDR) 350,000 UK Biobank participants suggest that genetically shorter telomere length increases the risk of hypothyroidism and decreases the risk of thyroid cancer, lymphoma, and a range of proliferative conditions. Our results replicate previously reported associations with increased risk of coronary artery disease and lower risk for multiple cancer types. Our findings substantially expand current knowledge on genes that regulate LTL and their impact on human health and disease.Peer reviewe

    Genetic correlations and genome-wide associations of cortical structure in general population samples of 22824 adults

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    Cortical thickness, surface area and volumes vary with age and cognitive function, and in neurological and psychiatric diseases. Here we report heritability, genetic correlations and genome-wide associations of these cortical measures across the whole cortex, and in 34 anatomically predefined regions. Our discovery sample comprises 22,824 individuals from 20 cohorts within the Cohorts for Heart and Aging Research in Genomic Epidemiology (CHARGE) consortium and the UK Biobank. We identify genetic heterogeneity between cortical measures and brain regions, and 160 genome-wide significant associations pointing to wnt/ÎČ-catenin, TGF-ÎČ and sonic hedgehog pathways. There is enrichment for genes involved in anthropometric traits, hindbrain development, vascular and neurodegenerative disease and psychiatric conditions. These data are a rich resource for studies of the biological mechanisms behind cortical development and aging
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