Thermophysical Properties of Fe-Si and Cu-Pb Melts and Their Effects on Solidification Related Processes

Among thermophysical properties, the surface/interfacial tension, viscosity, and density/molar volume of liquid alloys are the key properties for the modelling of microstructural evolution during solidification. Therefore, only reliable input data can yield accurate predictions preventing the error propagation in numerical simulations of solidification related processes. To this aim, the thermophysical properties of the Fe-Si and Cu-Pb systems were analysed and the connections with the peculiarities of their mixing behaviours are highlighted. Due to experimental difficulties related to reactivity of metallic melts at high temperatures, the measured data are often unreliable or even lacking. The application of containerless processing techniques either leads to a significant improvement of the accuracy or makes the measurement possible at all. On the other side, accurate model predicted property values could be used to compensate for the missing data; otherwise, the experimental data are useful for the validation of theoretical models. The choice of models is particularly important for the surface, transport, and structural properties of liquid alloys representing the two limiting cases of mixing, i.e., ordered and phase separating alloy systems

Fecal microbiota and inflammatory and antioxidant status of obese and lean dogs, and the effect of caloric restriction

IntroductionObesity is the most common nutritional disease in dogs, and is generally managed by caloric restriction. Gut microbiota alteration could represent a predisposing factor for obesity development, which has been associated with a low-grade inflammatory condition and an impaired antioxidant status. Besides, weight loss has been shown to influence the gut microbiota composition and reduce the inflammatory response and oxidative stress. MethodHowever, these insights in canine obesity have not been fully elucidated. The aim of this study was to assess the differences in serum and inflammatory parameters, antioxidant status, fecal microbiota and bacterial metabolites in 16 obese and 15 lean client-owned dogs and how these parameters in obese may be influenced by caloric restriction. First, for 30 days, all dogs received a high-protein, high-fiber diet in amounts to maintain their body weight; later, obese dogs were fed for 180 days the same diet in restricted amounts to promote weight loss. ResultsBefore the introduction of the experimental diet (T0), small differences in fecal microbial populations were detected between obese and lean dogs, but bacterial diversity and main bacterial metabolites did not differ. The fecal Dysbiosis Index (DI) was within the reference range (< 0) in most of dogs of both groups. Compared to lean dogs, obese dogs showed higher serum concentrations of acute-phase proteins, total thyroxine (TT4), and antioxidant capacity. Compared to T0, dietary treatment affected the fecal microbiota of obese dogs, decreasing the abundance of Firmicutes and increasing Bacteroides spp. However, these changes did not significantly affect the DI. The caloric restriction failed to exert significative changes on a large scale on bacterial populations. Consequently, the DI, bacterial diversity indices and metabolites were unaffected in obese dogs. Caloric restriction was not associated with a reduction of inflammatory markers or an improvement of the antioxidant status, while an increase of TT4 has been observed. DiscussionIn summary, the present results underline that canine obesity is associated with chronic inflammation. This study highlights that changes on fecal microbiota of obese dogs induced by the characteristics of the diet should be differentiated from those that are the consequence of the reduced energy intake

Fecal Microbiota, Bile Acids, Sterols, and Fatty Acids in Dogs with Chronic Enteropathy Fed a Home-Cooked Diet Supplemented with Coconut Oil

: Medium-chain fatty acids (MCFAs) are considered to be interesting energy sources for dogs affected by chronic enteropathies (CE). This study analyzed the clinical scores, fecal microbiota, and metabolomes of 18 CE dogs fed a home-cooked diet (HCD) supplemented with virgin coconut oil (VCO), a source of MCFA, at 10% of metabolizable energy (HCD + VCO). The dogs were clinically evaluated with the Canine Chronic Enteropathy Activity Index (CCECAI) before and at the end of study. Fecal samples were collected at baseline, after 7 days of HCD, and after 30 days of HCD + VCO, for fecal score (FS) assessment, microbial analysis, and determination of bile acids (BA), sterols, and fatty acids (FA). The dogs responded positively to diet change, as shown by the CCECAI improvement (p = 0.001); HCD reduced fecal fat excretion and HCD + VCO improved FS (p < 0.001), even though an increase in fecal moisture occurred due to HCD (p = 0.001). HCD modified fecal FA (C6:0: +79%, C14:0: +74%, C20:0: +43%, C22:0: +58%, C24:0: +47%, C18:3n-3: +106%, C20:4n-6: +56%, and monounsaturated FA (MUFA): -23%, p < 0.05) and sterol profile (coprostanol: -27%, sitostanol: -86%, p < 0.01). VCO increased (p < 0.05) fecal total saturated FA (SFA: +28%, C14:0: +142%, C16:0 +21%, C22:0 +33%) and selected MCFAs (+162%; C10:0 +183%, C12:0 +600%), while reducing (p < 0.05) total MUFA (-29%), polyunsaturated FA (-26%), campesterol (-56%) and phyto-/zoosterols ratio (0.93:1 vs. 0.36:1). The median dysbiosis index was <0 and, together with fecal BA, was not significantly affected by HCD nor by VCO. The HCD diet increased total fecal bacteria (p = 0.005) and the abundance of Fusobacterium spp. (p = 0.028). This study confirmed that clinical signs, and to a lesser extent fecal microbiota and metabolome, are positively influenced by HCD in CE dogs. Moreover, it has been shown that fecal proportions of MCFA increased when MCFAs were supplemented in those dogs. The present results emphasize the need for future studies to better understand the intestinal absorptive mechanism of MCFA in dogs

Heat-flow variability of suspended timber ground floors: Implications for in-situ heat-flux measuring

Reducing space heating energy demand supports the UK’s legislated carbon emission reduction targets and requires the effective characterisation of the UK’s existing housing stock to facilitate retrofitting decision-making. Approximately 6.6 million UK dwellings pre-date 1919 and are predominantly of suspended timber ground floor construction, the thermal performance of which has not been extensively investigated. This paper examines suspended timber ground floor heat-flow by presenting high resolution in-situ heat-flux measurements undertaken in a case study house at 15 point locations on the floor. The results highlight significant variability in observed heat-flow: point U-values range from 0.56 ± 0.05 to 1.18 ± 0.11 Wm−2 K−1. This highlights that observing only a few measurements is unlikely to be representative of the whole floor heat-flow and the extrapolation from such point values to whole floor U-value estimates could lead to its over- or under- estimation. Floor U-value models appear to underestimate the actual measured floor U-value in this case study. This paper highlights the care with which in-situ heat-flux measuring must be undertaken to enable comparison with models, literature and between studies and the findings support the unique, high-resolution in-situ monitoring methodology used in this study for further research in this area

Thermochemistry of RPdAl (R = rare earth metal) intermetallics

The standard enthalpies of formation at 300 K of the RPdAl phases (R = Nd, Sm, Gd, Tb, Dy, Ho and Er) have been obtained by using a high-temperature direct reaction drop calorimeter. The reliability of the calorimetric results has been determined and supported by using different analytical techniques: light optical microscopy, scanning electron microscopy equipped with electron probe microanalysis (EPMA with EDS detector) and X-ray Powder Diffraction analysis. The high exothermal values observed for the RPdAl phases are discussed and compared with those available for the binary compounds of the R-Pd systems and for the ternary RNiAl phases

Thermochemical investigation of Sm-Mg alloys

The paper focuses on the thermochemical behaviour of the binary Sm-Mg alloys. The enthalpies of formation of the Sm-Mg intermetallic compounds have been determined at 300 K by high temperature direct synthesis calorimetry. The following results in kJ/mole of atoms are reported: -18.5\ub12 (SmMg), -16.0\ub12 (SmMg2), -12.0\ub12 (SmMg3), -8.5\ub12 (SmMg5) and -5.5\ub12 (Sm5Mg41). The results are compared with the earlier experimental value obtained by vapour pressure

Al-Ti-Zn System: thermochemistry of the Ti(Zn,Al)3 phases

Cubic cP4-AuCu3 trialuminides have long been of interest because of their possible use as low density, high-temperature structural materials. The inherent brittleness of trialuminides, however, has limited their use in such applications so, many of the efforts to increase the ductility of these alloys have focused on identifying alloying additions that can lead to the stability of the cubic cP4-AuCu3 phase, rather than the tetragonal (tI8-Al3Ti or tI16-Al11Ti5) structures that form in most binary trialumides. These phases are also of interest for their possible use as precipitates for high-temperature, creep-resistant Al-based alloys (i.e. Al3Sc precipitates have been successfully used to increase the creep resistance of Al alloys). The design of new alloys requires accurate knowledge of the thermodynamic stability of all relevant phases which may be integrated within CALPHAD formalism to calculate binary and ternary phase diagrams and phase transformation driving forces. A high temperature drop calorimeter has been employed to determine the standard entalpy of formation at 300K of the samples which consist in an appropriate amounts of Al, Ti and Zn powders weighed and mixed in a glove box and then pressed to obtain pellets. The compositions of the alloys were Ti(Zn,Al)3 with an Al content from 10 to 65 at% Al. After the measurements, composition and state of the samples were examined by means of microscopic analysis (optical and electron probe microanalysis) and powder X-ray diffraction methods. We faced some experimental problems due to intrinsic factors that may be unfavorable in finding an optimum condition for calorimetric runs (i.e. large difference in melting point between Ti, Al and Zn, high vapor pressure of Zn). The results obtained by calorimetry, X-ray diffraction analysis and electron probe microanalysis, are here presented and discussed

The Gd\u2013Ni\u2013Al system: phases formation and isothermal sections at 500\ub0C and 800\ub0C

Phase relations in the Gd-Ni-Al ternary system have been established for two isothermal sections (500 and 800\ub0C) based on X-ray powder diffraction analysis (XRD), Light Optical Microscopy (LOM), Scanning Electron Microscopy (SEM) coupled with Energy dispersive Microprobe Analysis (EPMA) on about 31 annealed alloys in the 50 - 100 at.% Al region. Seven intermetallic phases have been identified in samples annealed at 500\ub0C and 800\ub0C: Gd3Ni5Al19 (oS108-Gd3Ni5Al19), Gd4Ni6Al23 (mS66-Y4Ni6Al23), GdNiAl4 (oS24-YNiAl4), GdNiAl3 (oP20-YNiAl3), Gd3Ni7Al14 (hP72- Gd3Ni7Al14), GdNiAl2 (oS16-CuMgAl2) and GdNi2Al3 (hP18 GdNi2Al3). One additional ternary phase GdNi3Al9 (hR78-ErNi3Al9) has been found only in samples annealed at 800\ub0C. The isothermal sections have been determined and then compared, the crystal structures of the ternary phases have been confirmed and lattice parameters calculated