Performance Analysis of the R290 Variable Geometry Gas Ejector Application for Other Refrigerants

Ejector refrigeration systems are promising alternative to standard vapour compression refrigeration systems. They can be driven with low-grade heat or solar systems, which make them even more renewable solution aligned with global energy transition. By implementing the controllable ejector, it can adapt to variable operating conditions, ensuring the high efficiency of both the device and the overall performance of the system. However, as it is fluid-driven device, its geometry has to be designed for particular fluid and typically requires redesigning when being applied for new applications. The R290 variable geometry gas ejector has been thoroughly tested for various spindle positions which ensured its highly efficient operation at different conditions. In this study, the same geometry was tested for other natural refrigerants of similar thermodynamic properties, i.e.R600a and R1270. The CFD analysis was based on a set of operating points for ejector-based air conditioning system working during the summer period with characteristic temperatures at evaporator and condenser. The controllable ejector was simulated for all the points with similar motive and suction nozzle parameters and the critical temperature at the outlet was determined. The analysis showed that the ejector can be used with other refrigerants maintaining high efficiency without any changes in geometry but for lower number of spindle positions. The obtained critical temperature indicates that with all the tested refrigerants the ejector-based cycle is able to work for cooling purposes during typical summer conditions for a wide range of temperatures

Crop Quality and Utilization: A Twelve-Hour In Vitro Procedure for Sorghum Grain Feed Quality Assessment

Improvedmethods for assessing cereal crop feed value are a prerequisite for the genetic improvement of sorghum [Sorghum bicolor (L.) Moench] feed value. Rate of starch digestion is now commonly believed to be the limiting factor in sorghum utilization by cattle (Bos taurus). However, techniques to assess this trait are not useful to sorghum breeders because of high labor inputs, lab error associated with starch measurement, and need for high numbers of replications. The objective of this study was to develop a simple technique capable of identifying differences in digestion between sorghum and corn (Zea mays L.) and detecting differences among sorghum genotypes. In vitro starch and dry matter digestion were measured on sorghum and corn lab standards at 0, 6, 12, 18, 24, 30, and 40 h. Maximum differentiation between corn and sorghum dry matter digestion (345 vs. 253 g kg21) and starch digestion (403 vs. 301 g kg21) occurred at 12 h, and dry matter and starch digestion were highly correlated. Differences among five sorghum lines were significant for 12-h dry matter digestion and ranged from 229 to 272 g kg21. This procedure provides a precise and rapid technique that can be used by feed grain breeders to evaluate modifications in grain digestion parameters

Direct synthesis of acyl fluorides from carboxylic acids using benzothiazolium reagents

2-(Trifluoromethylthio)benzothiazolium triflate (BT-SCF3) was used as deoxyfluorinating reagent for the synthesis of versatile acyl fluorides directly from the corresponding carboxylic acids. These acyl fluorides were reacted with amines in a one-pot protocol to form different amides, including dipeptides, under mild and operationally simple conditions in high yields. Mechanistic studies suggest that BT-SCF3 can generate acyl fluorides from carboxylic acids via two distinct pathways, which allows the deoxyfluorinating reagent to be employed in sub-stoichiometric amounts

Growing and Handling of Bacterial Cultures within a Shared Core Facility for Integrated Structural Biology Program

We have established and optimized standard operating procedures for growing and handling bacterial cultures in a shared core laboratory to support Integrative Structural Biology. The Integrative Structural Biology effort within the Biomolecular Research Center allows researchers to generate new knowledge about protein and RNA structure and function. We aim to understand how biomolecules assemble into stable structures and how structural dynamics impacts their function. Here we describe specific procedures for growing and handling bacterial cultures for overexpression and isolation of recombinant proteins, 15N/13C uniform labeling of recombinant proteins, protein isolation and purification, and analysis of protein solubility that are ideal for implementation in a shared research core laboratory that serves a multitude of diverse customers and research laboratories

XML-structured documents: Retrievable units and inheritance

We consider the retrieval of XML-structured documents, and of passages from such documents, defined as elements of the XML structure. These are considered from the point of view of passage retrieval, as a form of document retrieval. A retrievable unit (an element chosen as defining suitable passages for retrieval) is a textual document in its own right, but may inherit information from the other parts of the same document. Again, this inheritance is defined in terms of the XML structure. All retrievable units are mapped onto a common field structure, and the ranking function is a standard document retrieval function with a suitable field weighting. A small experiment to demonstrate the idea, using INEX data, is described

Integrate and Fire Neural Networks, Piecewise Contractive Maps and Limit Cycles

We study the global dynamics of integrate and fire neural networks composed of an arbitrary number of identical neurons interacting by inhibition and excitation. We prove that if the interactions are strong enough, then the support of the stable asymptotic dynamics consists of limit cycles. We also find sufficient conditions for the synchronization of networks containing excitatory neurons. The proofs are based on the analysis of the equivalent dynamics of a piecewise continuous Poincar\'e map associated to the system. We show that for strong interactions the Poincar\'e map is piecewise contractive. Using this contraction property, we prove that there exist a countable number of limit cycles attracting all the orbits dropping into the stable subset of the phase space. This result applies not only to the Poincar\'e map under study, but also to a wide class of general n-dimensional piecewise contractive maps.Comment: 46 pages. In this version we added many comments suggested by the referees all along the paper, we changed the introduction and the section containing the conclusions. The final version will appear in Journal of Mathematical Biology of SPRINGER and will be available at http://www.springerlink.com/content/0303-681

Light quark masses and pseudoscalar decay constants from Nf=2 Lattice QCD with twisted mass fermions

We present the results of a lattice QCD calculation of the average up-down and strange quark masses and of the light meson pseudoscalar decay constants with Nf=2 dynamical fermions. The simulation is carried out at a single value of the lattice spacing with the twisted mass fermionic action at maximal twist, which guarantees automatic O(a)-improvement of the physical quantities. Quark masses are renormalized by implementing the non-perturbative RI-MOM renormalization procedure. Our results for the light quark masses are m_ud^{msbar}(2 GeV)= 3.85 +- 0.12 +- 0.40 MeV, m_s^{msbar}(2 GeV) = 105 +- 3 +- 9 MeV and m_s/m_ud = 27.3 +- 0.3 +- 1.2. We also obtain fK = 161.7 +- 1.2 +- 3.1 MeV and the ratio fK/fpi=1.227 +- 0.009 +- 0.024. From this ratio, by using the experimental determination of Gamma(K-> mu nu (gamma))/Gamma(pi -> mu nu (gamma)) and the average value of |Vud| from nuclear beta decays, we obtain |Vus|=0.2192(5)(45), in agreement with the determination from Kl3 decays and the unitarity constraint.Comment: 20 pages, 5 figure