NRC-12

Objective: This study determined the physical properties and cytotoxicity of a novel root-end filling material (NRC). Study design: NRC is a powder and liquid system. The liquid is composed of hydroxyethylmethacrylate, benzoyl peroxide, toluidine, and toluenesulfinate. And the powder is made of calcium oxide, calcium silicate, and triphenylbismuth carbonate. The setting time, compressive strength, and pH change of NRC and gray and white mineral trioxide aggregate (MTA) were determined according to ISO standardization. MC3T3-E1 cells were cultured on NRC and white MTA for determining MTT scores. The absorbance of formazan was measured at 570 nm with a spectrophotometer. The MTT assay was performed in triplicate and repeated in 2 cultures. One-way analysis of variance was used to determine statistical differences in physical properties and MTT assay (P < .05). Results: Mean setting time of materials tested were: NRC 12.5 +/- 0.3 minutes, gray MTA 345.5 +/- 96.2 minutes, and white MTA 318.0 +/- 56.0 minutes. After 24 hours, the mean compressive strengths were: NRC, 21.6 +/- 5.5 MPa, gray MTA: 7.7 +/- 3.3 MPa, and white MTA, 18.9 +/- 3.2 MPa. The pH of the test materials were: NRC 12.0, gray MTA 12.2, and white MTA 11.9. There were no statistically significant differences in compressive strength and pH between white MTA and NRC. The compressive strength of gray MTA was significantly lower than white MTA and NRC (P < .05). The setting time of NRC was significantly lower than white and gray MTA. In MTT assay, both NRC and white MTA were not cytotoxic to MC3T3-E1 cells. Conclusions: It was concluded that the setting time, compressive strength, pH, and initial biocompatibility results of NRC are favorable for a root-end filling material.

In plant breeding programs, screening for drought-tolerance is often a bottleneck. An experiment was conducted in the field and rainout shelters to: (1) identify physiological traits in breeding programs that can be used as criteria for selecting drought tolerance soybean genotypes [Glycine max (L.) Merr], (2) evaluate genotypic differences to drought tolerance, and (3) identify genotypes with superior drought tolerance. Sixteen genotypes were evaluated in split plot design under irrigated and drought conditions. Various physiological traits were measured in irrigated and drought stressed plants such as canopy temperature, root length, specific leaf weight, photosynthetic rate, chlorophyll, and epicuticular wax content. As compared with irrigated conditions, the percent reduction in mean soybean yield under rainout shelter was 40%. The mean yields of soybean genotypes ranged from 1162 kg/ha (NRC 12) to 2610 kg/ha (JS 335) under irrigated conditions, whereas, under water stress conditions, yields ranged from 852 kg/ha (Samrat) to 1654 kg/ha (EC 538828). Genotypes EC 538828, JS 97-52, EC 456548, and EC 602288 had better avoidance to drought than other genotypes. The superior drought tolerance of the four genotypes was related to their low canopy temperature, deep root system, and high values for root/shoot weight ratio, specific leaf weight, chlorophyll content, photosynthetic rate, epicuticular wax content, and Photosystem II (PSII) efficiency. Therefore, when genetic diversity of these physiological traits is established in breeding programs, these traits can be used as a selection criterion for selecting drought tolerant genotypes.

The objectives of this study were to evaluate heat stress feed intake models for growing swine using a data set assembled from the literature and to develop a series of new equations modeling the influence of the thermal environment and interactions between the thermal environmental and other factors on feed intake. A literature survey was conducted to identify studies assessing intake responses to temperature. The resulting data set comprised 35 studies containing 120 comparisons to thermoneutral intake. Intake as a fraction of thermoneutral intake (FFI) was the primary response variable, where a value of 1 represented no change from thermoneutral intake. The FFI predicted by NRC and a recent model from a meta-analysis (Renaudeau et al.,) were compared to observed values. New parameters for the NRC equation (NRCmod) were derived, and a series of new equations incorporating duration of exposure (TD), temperature cycling (TC), and floor type (TH) were also derived. Root-mean-square prediction error (RMSPE) and concordance correlation coefficients were used to evaluate all models. The RMSPE for the NRC model was 23.6 with mean and slope bias accounting for 12.6% and 51.1% of prediction error, respectively. The TD, TC, and TH models had reduced RMSPE compared with NRC: 12.9 for TD, 12.6 for TC, and 12.9 for TS. Substantial improvements were also made by refitting parameters (NRCmod; RMSPE 13.0%). In NRCmod, TD, TC, and TH, random error was the predominant source, accounting for over 97% of prediction error. The Renaudeau et al. model was also evaluated. Renaudeau et al. had relatively low RMSPE (22.3) for intake but higher RMSPE for FFI (22.6) than NRC, NRCmod, TD, TC, or TH. Additional parameters were derived for the Renaudeau et al. equation to account for housing system and diet characteristics. This adjustment reduced RMSPE of predicting feed intake (16.0) and FFI (16.3) and reduced systematic bias in the equation. This evaluation of equations highlights the effects of novel explanatory variables on feed intake during heat stress, and the comparison can be useful when selecting a model that best explains variability in feed intake responses to heat stress given available input data.