Substrate-Assisted Catalysis Unifies Two Families of Chitinolytic Enzymes

Hen egg-white lysozyme has long been the paradigm for enzymatic glycosyl hydrolysis with retention of configuration, with a protonated carboxylic acid and a deprotonated carboxylate participating in general acid-base catalysis. In marked contrast, the retaining chitin degrading enzymes from glycosyl hydrolase families 18 and 20 all have a single glutamic acid as the catalytic acid but lack a nucleophile on the enzyme. Both families have a catalytic (βα)8-barrel domain in common. X-ray structures of three different chitinolytic enzymes complexed with substrates or inhibitors identify a retaining mechanism involving a protein acid and the carbonyl oxygen atom of the substrate’s C2 N-acetyl group as the nucleophile. These studies unambiguously demonstrate the distortion of the sugar ring toward a sofa conformation, long postulated as being close to that of the transition state in glycosyl hydrolysis.

Integration of Multi-Stage Membrane Carbon Capture Processes to Coal-Fired Power Plants using highly permeable polymers

Membrane separation systems could be a feasible option as post combustion carbon capture technologies in coal-fired power plants. Recent advancement on membrane materials based on microporous super glassy polymers could improve significantly the capture process but the properties of the materials have to guide the design of the separation stage. In this study an advanced hybrid two-stage membrane process employing one of the most permeable polymer known (PIM-1) is retrofitted to a coal fired power plant and the process is analysed in terms of energy requirement and cost performance. The results are based on the use of an in-house detailed membrane module model implemented in UniSim Design®, the Honeywell process flowsheet simulator. The study indicates the need for advanced configuration in order for highly permeable membranes to be competitive with more mature technologies in terms of capture cost. The effect of ageing and impurities on the material is also investigated in order to predict the decline in process performance over time and suggest a timeproof design. Keywords: Membranes, PIMs, Post-combustion, LCO

Optimal coupling of waste and concentrated solar for the constant production of electricity over a year

[EN]In this paper a biogas-based Brayton cycle is integrated with a concentrated solar power facility. The gas turbine hot flue gas and the molten salts are used to generate steam for the regenerative Rankine cycle. The process model is solved as a non-linear optimization problem within a multiperiod scheme to decide on the contribution of the energy resources and the operating conditions of the facility to meet a certain demand of power over a year mitigating the absence of solar availability. The steam turbine is responsible for power production while the gas turbine works mainly as a combustion chamber. In the South of Spain an excess of biogas is available during summer yielding a production cost of electricity of 0.17€/kWh with an investment of 380 M€ for a production facility of 25MW. This plant is not yet economic

Distributional impact of taxes and social transfers in Russia over the downturn

Low oil prices and the recession in Russia which started in 2014 are increasing pressures for fiscal consolidation, after more than a decade of prosperity. This paper assesses the distributional impact of the main tax and social spending programs in Russia in 2014 by applying a state-of-the-art incidence analysis. Overall, the Russian welfare state achieves a moderate reduction in inequality through tax-benefit policies by international standards. Most redistribution occurs through pensions. Major limits on the redistributive effect of tax-benefit policy include the large share of tax revenues that come from (regressive) indirect taxes, the neutral impact of personal income taxes and the low share of spending that goes on social assistance targeted to low-income groups. Tax-benefit policy also has an important impact on the age distribution of income, as households of working-age people (with and without children) subsidize pensioner households

Título: Tratado completo sobre los medios de conservar la salud, precaver, y curar las enfermedades.

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Medicina domestica, o casera, y tratado completo sobre los medios de conservar la salud, precaver, y curar las enfermedades ...

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Título: Tratado completo sobre los medios de conservar la salud, precaver, y curar las enfermedades.

Sign.: [@]2, A-Z4, 2A-2Z4, 3A-3R4

Fungaemia due to Cryptococcus laurentii and a review of non- neoformans cryptococcaemia

Cryptococcus laurentii is one of several non- neoformans cryptococci that have rarely been associated with human infection. The spectrum of clinical infection due to non- neoformans species ranges from skin lesions to fungaemia. Most cases of non- neoformans fungaemia have been noso-comially acquired and have been associated with indwelling intravascular catheters and neutropenia. Limited data on in vitro susceptibilities of non- neoformans cryptococci show these species to be more resistant to fluconazole and flucytosine than most Cr. neoformans. Two such cases are presented here. Zusammenfassung . Cryptococcus laurentii ist eine von mehreren nicht- neofomans-Cryptococcus -Arten, die selten mit Krankheiten am Menschen in Zusammenhang gebracht werden. Das Spektrum durch Nicht- neoformans -Arten bedingter klinischer Infektionen reicht von HautlÄsionen bis zur FungÄmie. Die Mehrzahl der FÄlle von nicht- neoformans -FungÄmie waren nosokomial bedingt und mit intravasalen Dauerkathetern und Neutropenie assoziiert. Die wenigen Daten Über In-vitro-SuszeptibilitÄt von Non- neoformans -Arten fÜr Fluconazol und Flucytosin sprechen dafÜr, daß diese Arten resistenter als die meisten Cr. neoformans-StÄmme sind. Zwei solcher FÄlle werden vorgestellt.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72398/1/j.1439-0507.1998.tb00338.x.pd