178,492 research outputs found
Chemo-enzymatic Synthesis of Ethyl (R)-2-hydroxy-4-phenylbutyrate
No full textA new biocatalytic strategy to obtain the ethyl (R)-2-hydroxy-4-oxo-4-phenylbutyrate precursor of ethyl
(R)-2-hydroxy-4-phenylbutyrate, an important intermediate in the synthesis of a variety of ACE inhibitors,
has been set up. Starting from ethyl 2,4-dioxo-4-phenylbutyrate, a screen of microorganisms has
been performed in order to find the best catalyst able to reduce the keto group in the a-position with high
chemo- and enantioselectivity. The biotransformation catalyzed by Pichia pastoris CBS 704 gave the best
results in terms of conversion and enantioselectivity. The addition of adsorbing resins in the fermentation
medium is effective in controlling substrate and product concentration in the medium, thus improving
both conversion and enantioselectivity of the biotransformation. Preliminary experiments in a continuous
batch reactor with growing culture of P. pastoris will be also presented
Biotransformation of unsaturated aldehydes by microorganisms with pyruvate decarboxylase activity
No full textAppropriate Similarity Measures for Author Cocitation Analysis
No full textWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
A Code for the Preliminary Design of Cooled Supercritical CO2 Turbines and Application to the Allam Cycle
No full textThis paper documents a thermo-fluid-dynamic mean-line model for the preliminary design of multistage axial turbines with blade cooling applicable to supercritical CO2 turbines. Given the working fluid and coolant inlet thermodynamic conditions, blade geometry, number of stages and load criterion, the model computes the stage-by-stage design along with the cooling requirement and ultimately provides an estimate of turbine efficiency via a semi-empirical loss model. Different cooling modes are available and can be selected by the user (stand-alone or combination): convective cooling, film cooling, and thermal barrier coating. The model is applied to attain the preliminary aero-thermal design of the 600 MW cooled axial supercritical CO2 turbine of the Allam cycle. Results show that a load coefficient varying from 3 to 1 throughout the machine, and a reaction degree ranging from 0.1 to 0.5 lead to the maximum total-to-static turbine efficiency of about 85%. Consequently, as opposed to uncooled CO2 turbines, a repeated stage configuration is an unsuited design choice for cooled sCO2 machines. Moreover, the study highlights that film cooling is considerably less effective compared to conventional gas turbines, while increasing the number of stages from 5 to 6 and adopting higher rotational speeds leads to an increased efficiency
"Closing the R&D Gap, Evaluating the Sources of R&D Spending"
No full textBoth spending and tax policies have been implemented in the United States with the goal of stimulating private sector research and development (R&D). Karier questions whether current R&D policy, especially the research and experimentation tax credit, can contribute to closing the gap between nondefense expenditures on R&D in the United States and such expenditures in other countries, such as Japan and Germany. He also explores possible changes to our current R&D policy to make it more effective.
Hepatic encephalopathy after transjugular intrahepatic portosystemic shunt Incidence and risk factors
No full textForty-seven consecutive patients were prospectively evaluated to study the incidence of hepatic encephalopathy as well as modifications in the PSE index after TIPS, Various clinical, laboratory, and angiographic parameters were also recorded to identify risk factors for the development of post-TIPS hepatic encephalopathy (HE), Mean follow-up was 17 +/- 7 months. During follow-up, six patients died and one underwent transplantation, All other patients were followed for at least a year, Fifteen patients (32%) experienced 20 acute episodes of precipitated HE (hospitalization was necessary in 10 instances), and five patients (11%) presented a continuous alteration in mental status with frequent spontaneous exacerbation during follow-up, Both precipitated and spontaneous HE occurred more frequently during the first three months of follow-up, Moreover the PSE index was significantly worse than basal values one month after TIPS, thereafter returning to near basal values, HE was successfully treated in all patients but one who required a reduction in the stent/shunt diameter. Increasing age (>65 years) and low portacaval gradient (10 mm Hg to avoid an unacceptable rate of HE after TIPS
Spectroscopic methods for distinguishing tricyclic cannabinoids from "abnormal" synthetic isomers.
No full textGoing Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
A proposito della corruptio servi: questioni terminologiche
No full textla lingua del diritto e quella quotidiana: indagine sui termini della corruptio servi e i verbi ad essa relativi nel linguaggio guridic
- …
