778 research outputs found

    Characterization of a thermostable methylaspartate ammonia lyase from Carboxydothermus hydrogenoformans

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    Methylaspartate ammonia lyase (MAL; EC 4.3.1.2) catalyzes the reversible addition of ammonia to mesaconate to give (2S,3S)-3-methylaspartate and (2S,3R)-3-methylaspartate as products. MAL is of considerable biocatalytic interest because of its potential use for the asymmetric synthesis of substituted aspartic acids, which are important building blocks for synthetic enzymes, peptides, chemicals, and pharmaceuticals. Here, we have cloned the gene encoding MAL from the thermophilic bacterium Carboxydothermus hydrogenoformans Z-2901. The enzyme (named Ch-MAL) was overproduced in Escherichia coli and purified to homogeneity by immobilized metal affinity chromatography. Ch-MAL is a dimer in solution, consisting of two identical subunits (āˆ¼49Ā kDa each), and requires Mg(2+) and K(+) ions for maximum activity. The optimum pH and temperature for the deamination of (2S,3S)-3-methylaspartic acid are 9.0 and 70Ā°C (k(cat)ā€‰=ā€‰78Ā s(āˆ’1) and K(m)ā€‰=ā€‰16Ā mM). Heat inactivation assays showed that Ch-MAL is stable at 50Ā°C for >4Ā h, which is the highest thermal stability observed among known MALs. Ch-MAL accepts fumarate, mesaconate, ethylfumarate, and propylfumarate as substrates in the ammonia addition reaction. The enzyme also processes methylamine, ethylamine, hydrazine, hydroxylamine, and methoxylamine as nucleophiles that can replace ammonia in the addition to mesaconate, resulting in the corresponding N-substituted methylaspartic acids with excellent diastereomeric excess (>98% de). This newly identified thermostable MAL appears to be a potentially attractive biocatalyst for the stereoselective synthesis of aspartic acid derivatives on large (industrial) scale. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s00253-011-3615-6) contains supplementary material, which is available to authorized users

    Factors influencing e-diplomacy implementation: Exploring causal relationships using interpretive structural modelling

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    YesElectronic diplomacy (E-diplomacy) is the use of technology by nations to define and establish diplomatic goals and objectives and to efficiently carry out the functions of diplomats. These functions include representation and promotion of the home nation, establishing both bilateral and multilateral relations, consular services and social engagement. It encapsulates the adoption of multiple ICT tools over the Internet to support a nationā€™s interests in other countries while ensuring that foreign relations are improved between the countries. Given its embryonic nature, little scholarly research has been undertaken to study its influence on diplomatic functions and the various factors that influence its implementation. This paper applies the Interpretative Structural Modelling (ISM) methodological approach to identify factors that impact the implementation of e-diplomacy and to determine their causal relationship and rankings. This study applies the ISM methodology to the subject of e-diplomacy. The ISM-based model provides a framework for practitioners to aid decision-making and manage the implementation of e-diplomacy

    Fast approximation of small pā€values in permutation tests by partitioning the permutations

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    Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/142988/1/biom12731_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/142988/2/biom12731.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/142988/3/biom12731-sup-0001-SuppData.pd

    Effectiveness and cost-effectiveness of early assisted discharge for Chronic Obstructive Pulmonary Disease exacerbations: the design of a randomised controlled trial

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    Background: Exacerbations of Chronic Obstructive Pulmonary Disease (COPD) are the main cause for hospitalisation. These hospitalisations result in a high pressure on hospital beds and high health care costs. Because of the increasing prevalence of COPD this will only become worse. Hospital at home is one of the alternatives that has been proved to be a safe alternative for hospitalisation in COPD. Most schemes are early assisted discharge schemes with specialised respiratory nurses providing care at home. Whether this type of service is cost-effective depends on the setting in which it is delivered and the way in which it is organised. Methods/Design: GO AHEAD (Assessment Of Going Home under Early Assisted Discharge) is a 3-months, randomised controlled, multi-centre clinical trial. Patients admitted to hospital for a COPD exacerbation are either discharged on the fourth day of admission and further treated at home, or receive usual inpatient hospital care. Home treatment is supervised by general nurses. Primary outcome is the effectiveness and cost effectiveness of an early assisted discharge intervention in comparison with usual inpatient hospital care for patients hospitalised with a COPD exacerbation. Secondary outcomes include effects on quality of life, primary informal caregiver burden and patient and primary caregiver satisfaction. Additionally, a discrete choice experiment is performed to provide insight in patient and informal caregiver preferences for different treatment characteristics. Measurements are performed on the first day of admission and 3 days, 7 days, 1 month and 3 months thereafter. Ethical approval has been obtained and the study has been registered. Discussion: This article describes the study protocol of the GO AHEAD study. Early assisted discharge could be an effective and cost-effective method to reduce length of hospital stay in the Netherlands which is beneficial for patients and society. If effectiveness and cost-effectiveness can be proven, implementation in the Dutch health care system should be considered. Trial registration: Netherlands Trial Register NTR1129

    Developing Composite Insulating Cross-Arms for 400 kV Lattice Towers

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    \u3cp\u3ePolymorphism of organic semiconducting materials exerts critical effects on their physical properties such as optical absorption, emission and electrical conductivity, and provides an excellent platform for investigating structureā€“property relations. It is, however, challenging to efficiently tune the polymorphism of conjugated polymers in aggregated, semi-crystalline phases due to their conformational freedom and anisotropic nature. Here, two distinctly different semi-crystalline polymorphs (Ī²\u3csub\u3e1\u3c/sub\u3e and Ī²\u3csub\u3e2\u3c/sub\u3e) of a low-bandgap diketopyrrolopyrrole polymer are formed through controlling the solvent quality, as evidenced by spectroscopic, structural, thermal and charge transport studies. Compared to Ī²\u3csub\u3e1\u3c/sub\u3e, the Ī²\u3csub\u3e2\u3c/sub\u3e polymorph exhibits a lower optical band gap, an enhanced photoluminescence, a reduced Ļ€-stacking distance, a higher hole mobility in field-effect transistors and improved photocurrent generation in polymer solar cells. The Ī²\u3csub\u3e1\u3c/sub\u3e and Ī²\u3csub\u3e2\u3c/sub\u3e polymorphs provide insights into the control of polymer self-organization for plastic electronics and hold potential for developing programmable ink formulations for next-generation electronic devices.\u3c/p\u3

    Organic-Inorganic Nanostructure Architecture via Directly Capping Fullerenes onto Quantum Dots

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    A new form of fullerene-capped CdSe nanoparticles (PCBA-capped CdSe NPs), using carboxylate ligands with [60] fullerene capping groups that provides an effective synthetic methodology to attach fullerenes noncovalently to CdSe, is presented for usage in nanotechnology and photoelectric fields. Interestingly, either the internal charge transfer or the energy transfer in the hybrid material contributes to photoluminescence (PL) quenching of the CdSe moieties.open2

    Advances in understanding ischemic acute kidney injury

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    Acute kidney injury (AKI) is independently associated with increased morbidity and mortality. Ischemia is the leading cause of AKI, and short of supportive measures, no currently available therapy can effectively treat or prevent ischemic AKI. This paper discusses recent developments in the understanding of ischemic AKI pathophysiology, the emerging relationship between ischemic AKI and development of progressive chronic kidney disease, and promising novel therapies currently under investigation. On the basis of recent breakthroughs in understanding the pathophysiology of ischemic AKI, therapies that can treat or even prevent ischemic AKI may become a reality in the near future
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