On the use of metastable interface equilibrium assumptions on prediction of solidification micro-segregation in laser powder bed fusion

ABSTRACT

Many models have been developed to explore solidification segregation and dendrite structure in additively manufactured parts. However, these models tend to be computationally expensive and consider only a limited number of alloying elements, compromising their practical application. In this work, a methodology to extend the Scheil model, based on interface metastable equilibrium assumptions, is established to predict the spatial compositional maps due to micro-segregation for a laser-powder bed fusion (L-PBF) build of alloy 718. The compositional maps are contrasted against experimental data measured in a unit dendrite cell by transmission electron microcopy. The validity of Scheil's implicit assumptions under the rapid solidification conditions in L-PBF is further discussed. The extended Scheil model is shown to be computationally efficient and readily applicable to multi-component systems.     

Analysis of cancer in histological images: employing an approach based on genetic algorithm

Pattern Analysis and Applications - The analysis of histological images is based on visual assessment of tissues by specialists using an optical microscopy. This task can be time-consuming and...     

A Hermite polynomial algorithm for detection of lesions in lymphoma images

Pattern Analysis and Applications - There are different types of lesions that can be investigated with the hematoxylin–eosin staining protocol. Lymphoma is a type of malignant disease which...     

Actual Evapotranspiration for Sugarcane Based on Bowen Ratio-Energy Balance and Soil Water Balance Models with Optimized Crop Coefficients

Water Resources Management - Evapotranspiration is an important parameter to evaluate soil water deficit and water use efficiency, especially in locations with irregularly distributed...     

Causal effect of prolificacy on milk yield in dairy sheep using propensity score

In animal production, it is often important to investigate causal relationships among variables. The gold standard tool for such investigation is randomized experiments. However, randomized experiments may not always be feasible, possible, or cost effective or reflect real-world farm conditions. Sometimes it is necessary to infer effects from farm-recorded data. Inferring causal effects between variables from field data is challenging because the association between them may arise not only from the effect of one on another but also from confounding background factors. Propensity score (PS) methods address this issue by correcting for confounding in different levels of the causal variable, which allows unbiased inference of causal effects. Here the objective was to estimate the causal effect of prolificacy on milk yield (MY) in dairy sheep using PS based on matched samples. Data consisted of 4,319 records from 1,534 crossbred ewes. Confounders were lactation number (first, second, and third through sixth) and dairy breed composition (<0.5, 0.5–0.75, and >0.75 of East Friesian or Lacaune). The causal variable prolificacy was considered as 2 levels (single or multiple lambs at birth). The outcome MY represented the volume of milk produced in the whole lactation. Pairs of single- and multiple-birth ewes (1,166) with similar PS were formed. The matching process diminished major discrepancies in the distribution of prolificacy for each confounder variable indicating bias reduction (cutoff standardized bias = 20%). The causal effect was estimated as the average difference within pairs. The effect of prolificacy on MY per lactation was 20.52 L of milk with a simple matching estimator and 12.62 L after correcting for remaining biases. A core advantage of causal over probabilistic approaches is that they allow inference of how variables would react as a result of external interventions (e.g., changes in the production system). Therefore, results imply that management and decision-making practices increasing prolificacy would positively affect MY, which is important knowledge at the farm level. Farm-recorded data can be a valuable source of information given its low cost, and it reflects real-world herd conditions. In this context, PS methods can be extremely useful as an inference tool for investigating causal effects. In addition, PS analysis can be implemented as a preliminary evaluation or a hypothesis generator for future randomized trials (if the trait analyzed allows randomization).     

UPLC-PDA–MS evaluation of bioactive compounds from leaves of Ilex paraguariensis with different growth conditions,treatments and ageing

Teas from Maté have been widely consumed for centuries in Brazil, Argentina, Paraguay, and Uruguay. We now determine how age, growth conditions and post-harvesting processes of leaves from Ilex paraguariensis affect the concentration of bioactive compounds and their antioxidant capacity. Phenolics, xanthines, and carbohydrates were identified and quantified by electrospray ionisation mass spectrometry (ESI-MS) and ultra performance liquid chromatography (UPLC), which dramatically reduces the time for each analysis (<3 min). On average, sun-exposed (monoculture) leaf extracts exhibited higher levels of bioactive compounds as compared to shaded (forest grown) ones. PCA (principal component analysis) analysis of all the samples indicated that those obtained after blanching and drying contained more phenolics and a smaller concentration of xanthine than those in natura. The oxidised leaves had lower concentrations of phenolics, and consequently a decline in antioxidant activity. No differences were found based on the leaf age.     

Efficacy of embryo transfer in lactating dairy cows during summer using fresh or vitrified embryos produced in vitro with sex-sorted semen

The objective was to determine whether transfer of fresh or vitrified embryos produced in vitro with sex-sorted semen improves pregnancy and calving rates during summer in lactating dairy cows compared with artificial insemination (AI). Lactating dairy cows (n = 722) were enrolled during summer months at 2 commercial dairies in Central Texas and randomly assigned to 1 of 3 treatments: AI with conventional semen (n = 227), embryo transfer-vitrified (ET-V; n = 279) or embryo transfer-fresh (ET-F; n = 216). Embryos were produced in vitro using sex-sorted semen and with Block-Bonilla-Hansen-7 culture medium. For vitrification, grade 1 expanded blastocysts were harvested on d 7 after fertilization and vitrified using the open-pulled straw method. Fresh embryos were grade 1 blastocysts and expanded blastocysts harvested on d 7 after fertilization. Cows were submitted to the Ovsynch56 protocol: d −10 GnRH, d −3 PGF_2α, d −1 GnRH and d 0 timed AI; or Select Synch protocol: d −9 GnRH, d −2 PGF_2α, and AI following detected estrus (day of AI = d 0). On d 7, all cows were examined for presence of a corpus luteum (CL). A vitrified or fresh embryo was transferred to cows with CL in ET-V and ET-F groups. Cows were considered synchronized if progesterone was <1 ng/mL on d 0 and a CL was present on d 7. At d 40 ± 7 of gestation, the percentage of cows pregnant was greater for the ET-F compared with the ET-V and AI groups among all cows (42.1 vs. 29.3 and 18.3%, respectively) and synchronized cows (45.5 vs. 31.6 and 24.8%, respectively). Also, the percentage of cows pregnant was greater for the ET-V than the AI group among all cows and tended to be greater among synchronized cows. At d 97 ± 7 of gestation, the percentage of cows pregnant among all cows was greater for ET-F and ET-V groups than for the AI group (36.4 and 25.7 vs. 17.0%, respectively) and the percentage for the ET-F group was greater than for the ET-V group. Among synchronized cows, the percentage of cows pregnant was significantly increased for the ET-F group than for ET-V and AI groups (39.4 vs. 27.8 and 23.1%, respectively) and no difference was found between ET-V and AI groups. No effect of treatment on embryo loss was observed. The percentage of cows with live births was significantly increased for the ET-F than for ET-V and AI groups among all cows (27.5 vs. 17.1 and 14.6%, respectively) and synchronized cows (29.9 vs. 18.5 and 20.0%, respectively). The percentage of cows giving birth to a live heifer was significantly increased for the ET-F and ET-V groups compared with the AI group among all cows (79.1 and 72.5 vs. 50.0%, respectively) and synchronized cows (79.1 and 72.5 vs. 50.0%, respectively). No difference existed between ET-F and ET-V groups for percent live heifer births but both were greater than for the AI group. The transfer of fresh embryos produced in vitro using sex-sorted semen to lactating dairy cows during summer can effectively increase the percentage of cows that establish pregnancy and also the percentage of cows that give birth to a live heifer compared with percentages from AI with conventional semen.