Statistical Mesoscopic Hydro-Thermodynamics: The Description of Kinetics and Hydrodynamics of Nonequilibrium Processes in Single Liquids

Hydrodynamics, a term apparently introduced by Daniel Bernoulli (1700-1783) to comprise hydrostatic and hydraulics, has a long history with several theoretical approaches. Here, after a descriptive introduction, we present so-called mesoscopic hydro-thermodynamics, which is also referred to as higher-order generalized hydrodynamics, built within the framework of a mechanical-statistical formalism. It consists of a description of the material and heat motion of fluids in terms of the corresponding densities and their associated fluxes of all orders. In this way, movements are characterized in terms of intermediate to short wavelengths and intermediate to high frequencies. The fluxes have associated Maxwell-like times, which play an important role in determining the appropriate contraction of the description (of the enormous set of fluxes of all orders) necessary to address the characterization of the motion in each experimental setup. This study is an extension of a preliminary article: Physical Review E \textbf{91}, 063011 (2015)

Managing variability in decision making in swine growing-finishing units

peer-reviewedAnalysis of data collected from pig farms may be useful to understand factors affecting pig health and productive performance. However, obtaining these data and drawing conclusions from them can be done at different levels and presents several challenges. In the present study, information from 688 batches of growing-finishing (GF) pigs (average initial and final body weight of 19.1 and 108.5 kg respectively) from 404 GF farms integrated in 7 companies was obtained between July 2008 and July 2010 in Spain by survey. Management and facility factors associated with feed conversion ratio (FCR) and mortality were studied by multiple linear regression analysis in each single company (A to G) and in an overall database (OD). Factors studied were geographic location of the farm, trimester the pigs entered the farm, breed of sire and sex segregation in pens (BREGENSEG), use of circovirus vaccine, number of origins the pigs were obtained from, age of the farm, percentage of slatted floor, type of feeder, drinker and ventilation, number of phases and form of feed, antibiotic administration system, water source, and number and initial weight of pigs. Results In two or more companies studied and/or in OD, the trimester when pigs were placed in the farm, BREGENSEG, number of origins of the pigs, age of the farm and initial body weight were factors associated with FCR. Regarding mortality, trimester of placement, number of origins of the pigs, water source in the farm, number of pigs placed and the initial body weight were relevant factors. Age of the farm, antibiotic administration system, and water source were only provided by some of the studied companies and were not included in the OD model, however, when analyzed in particular companies these three variables had an important effect and may be variables of interest in companies that do not record them. Conclusions Analysing data collected from farms at different levels helps better understand factors associated with productive performance of pig herds. Out of the studied factors trimester of placement and number of origins of the pigs were the most relevant factors associated with FCR and mortality.This research was supported by the Spanish Ministerio de Ciencia e Innovación (project AGL2011-29960). We also thank the Agencia Española de Cooperación Internacional para el Desarrollo (MAEC-AECID) for research fellowship

Processing of titanium aluminides by ceramic crucible induction melting

This work describes the processing results of TiAl alloys melted in controlled atmosphere induction furnace, using crucibles made of calcia and zirconia stabilised with yttria, calcia and magnesia, solidified and inside the crucible, in order to simulate the worst situation using this processing. In the results are presented segregation profiles of residual elements and its relation with micro hardness and “alpha-case” extension, in the microconstituents present at room temperatur

The production of TiAl by foundry processes

This paper describes a foundry technique that enables the production of TiAl employing an adapted melting procedure that uses an induction furnace with suitable refractory crucibles, inside a controlled atmosphere chamber. The developed technique allows the production of samples with a low and controlled amount of residual elements, with a thin superficial hard skin – known as “alpha-case” – and allows the use of higher superheating temperatures, when compared with alternative melting procedures. The micro-hardness and the residual contamination profiles, from the outside to the interior of samples, are presented and correlated to crucible refractory material and foundry practice.(undefined

Solubility of amino acids: a group-contribution model involving phase and chemical equilibria

A new model is proposed to represent the solubility behavior of 14 amino acids and 5 small peptides in water. The UNIFAC model is combined with a Debye-Huckel term to describe the activity coefficients of the species present in the biomolecule/water system. New groups have been defined according to the group-contribution concept, and chemical equilibrium is taken into account simultaneously with the physical equilibrium. To estimate the new interaction parameters, molal activity coefficient data from the literature were used. These parameters, in addition to solubility data, were the basis for the correlation of the solubility product of the amino acids. Using this approach, satisfactory results were obtained in the representation and prediction of the solubilities of amino acids in aqueous solutions at different conditions of temperature and pH

The role of intermolecular coupling in the photophysics of disordered organic semiconductors: Aggregate emission in regioregular polythiophene

We address the role of excitonic coulping on the nature of photoexcitations in the conjugated polymer regioregular poly(3-hexylthiophene). By means of temperature-dependent absorption and photoluminescence spectroscopy, we show that optical emission is overwhelmingly dominated by weakly coupled H-aggregates. The relative absorbance of the 0-0 and 0-1 vibronic peaks provides a powerfully simple means to extract the magnitude of the intermolecular coupling energy, approximately 5 and 30 meV for films spun from isodurene and chloroform solutions respectively.Comment: 10 pages, 4 figures, published in Phys. Rev. Let