Best-fit Equation Research Articles

A Prediction Model for the Intraocular Pharmacokinetics of Intravitreally Injected Drugs Based on Molecular Physicochemical Properties

Purpose: This study was aimed at determining the intraocular pharmacokinetics based on molecular physicochemical properties in a rabbit model. Methods: The entire dataset was obtained from previous literature, and research articles regarding 70 molecular compounds were investigated. The intravitreal half-lives in rabbit eyeballs of 22 macromolecules and 48 micromolecules were analyzed. Multiple linear regression analysis was carried out with non-collinear independent variables (molecular weight [MW] and lipophilicity) influencing intravitreal half-lives. The best-fit equations were selected based on the correlation coefficients and goodness-of-fit statistics. Results: The best-fit models obtained from the entire dataset, macromolecules, and micromolecules suggest the correlation between molecular physicochemical properties (MW and lipophilicity) and intravitreal half-life. Exclusion of outlier molecules (amphotericin B and foscarnet) leads to a better-fit correlation. MW is the definite single factor affecting intravitreal half-lives of macromolecules (Log t_1/2 = 0.148 + 0.370 Log MW, R² = 0.769), while both MW and lipophilicity influence the intraocular pharmacokinetics of micromolecules (Log t_1/2 = –1.213 + 0.762 Log MW – 0.115 Log p, R² = 0.554). Conclusion: The present study indicates that intravitreal half-life could be predicted based on molecular physicochemical properties (MW and lipophilicity). Also, increasing MW while reducing lipophilicity would be a reliable method for prolonging the intravitreal half-life of small chemical drugs, while MW is the single major determinant for large biologic drugs.

Phosphorus release kinetics and solubility capacity of phosphorus fractionation induced by organic acids from a black soil in northeast China

Phosphorus (P) fertilizers are added to improve the soil P fertility, but the rate of P release can greatly influence its availability. Organic acids are effective in the release of inorganic P (Pi), but the contribution of each Pifraction is not well understood. This study reported the transformation rate of P and solubility of Pifractions induced by organic acids. Path analysis was utilized to explore the direct and indirect effects of Pifractions on the amount of total Pi(TPi) solubilized. Results showed that the P release was initially rapid, followed by a slower release that lasted up to 2160 h, and the Elovich equation was the best-fitted kinetic equation to estimate the transformation rate of available P. The amount of TPi-solubilized by oxalic and citric acids tended to increase with increasing organic acid concentrations. Oxalic acid exhibited a lower TPi-solubility capability than citric acid when the organic acid concentration was ≤1 mmol L−1, whereas citric acid was higher at ≥1.5 mmol L−1. The Al-P-solubilized had the highest content of studied fractions, and path analysis revealed that the Al-P-solubilized exhibited a significant direct effect on TPi-solubilized. Thus, Al-P is a potential P source in black soil.

Normative Values of Second-Trimester Maternal Serum Markers Using an Automated Assay Platform for Down Syndrome Screening

Objective: Automated chemiluminescent immunoassay has several advantages over manual ELISA with comparable test performance. Few studies have reported the reference values of the second-trimester serum markers maternal serum alpha-fetoprotein (AFP), human chorionic gonadotropin (hCG), unconjugated estriol (uE3), and inhibin A (Inh A) by automated immunoassay in Asian population. Accordingly, this study aimed to determine the median values of second trimester serum markers as a function of gestational age (GA) in Thai population using an automated immunoassay. Methods: This prospective cross-sectional study of serum markers in healthy singleton second trimester (14-22 weeks) pregnant women was conducted at Siriraj Hospital from September 2012 to April 2015. Maternal serum AFP, hCG, uE3, and Inh A were analyzed by automated immunoassay. Predicted median values as a function of GA were calculated from best-fit regression equations. Results: A total of 1,526 women were included. Median values serum markers were constructed from the following optimal models: AFP (ng/mL) = 99.082 - 14.195 GA + 0.662 GA 2 , r 2 =0.995; hCG (mIU/mL) = 39, 0168.106 - 35 968.397GA + 876.708GA 2 , r 2 =0.972; uE3 (ng/mL) = -3.388 + 0.274 GA, r 2 =0.997; and, Inh-A (pg/mL) = 1,206.875 - 114.171 GA + 3.174 GA 2 , r 2 =0.882. Using the same platform analysis and maternal weight adjustment, the reference values in Thai population were shown to be different from those of other ethnicities. Conclusion: Median values of second-trimester serum markers for Thai population were determined. Maternal weight and the use of population-specific normal values have to be taken into account for Down syndrome screening in the second trimester.

Zinc release from Zn-Mg-Fe(III)-LDH intercalated with nitrate, phosphate and carbonate: The effects of low molecular weight organic acids

There is growing interest in using layered double hydroxides (LDH) as controlled release systems of essential nutrients for plants. The Zn-Mg-Fe(III)-LDH intercalated with nitrate (LDH-NO3−), phosphate (LDH-HPO42−) and carbonate (LDH-CO32−) were synthesized with the aim of investigation the effect of oxalic acid (OX), tartaric acid (TAR) and citric acid (CIT) (three common low molecular organic acids (LMWOAs) available in soil solution) to release structural Zn. In this regard, effects of time, initial pH and background electrolyte on the release of structural Zn from LDH in the presence of LMWOAs were performed based on the batch technique. According to the results, although the Zn-complexing abilities of organic acids were pH-dependent, the overall extent of Zn release was sensitive to the concentration of organic acid as well as to the type of available cation in the electrolyte solution and intercalated anion. Among the LMWOAs, CIT was the most effective ligand in releasing Zn, followed by OX and TAR. Also, our observation suggested that the intercalation of carbonate strongly suppressed the release of Zn in the absence and presence of organic acids, especially in CaCl2 electrolyte. The effect of organic acids on the kinetics of Zn release (KCl solution; initial pH = 6.0) were investigated and several kinetic models were tested to describe the time-dependent Zn release. Results showed that Elovich and pseudo-second order equations were the best-fit equations among five kinetic models used. The presence of the LMWOAs generally increased initial release rate (h) and the extent of Zn released at equilibrium (qe) from LDH; however, the enhancement effect of CIT was pronounced in LDH-NO3− and LDH-HPO42−.

Resistant starch reduces large intestinal pH and promotes fecal lactobacilli and bifidobacteria in pigs

Dietary resistant starch (RS) may have prebiotic properties but its effects on fermentation and the microbial population are inconsistent. This meta-analysis aimed to quantify the relationship between RS type 2 (RS2) and intestinal short-chain fatty acids (SCFA) and pH as well as certain key bacterial taxa for intestinal health in pigs. From the 24 included articles with sufficient information about the animal, and dietary and physiological measurements published between 2000 and 2017, individual sub-data sets for fermentation metabolites, pH, bacterial abundances and apparent total tract digestibility were built and used to parameterize prediction models on the effect of RS2, accounting for inter- and intra-study variability. In addition, the effect of pig’s BW at the start of the experiment and duration of the experimental period on response variables were also evaluated using backward elimination analysis. Dietary RS levels ranged from 0% to 78.0% RS, with median and mean RS levels of 28.8% and 23.0%, respectively. Negative relationships could be established between dietary RS and pH in the large intestine (P<0.05), with a stronger effect in the mid and distal colon, and feces (R2=0.64 to 0.81; P<0.001). A dietary level of 15% RS would lower the pH in the proximal, mid-, distal colon and feces by 0.2, 0.6, 0.4 and 0.6 units, respectively. Increasing RS levels, however, did not affect SCFA concentrations in the hindgut, but enhanced the molar proportion of propionate in mid-colon and reduced those of acetate in mid-colon and of butyrate in mid- and distal colon (R2=0.46 to 0.52; P<0.05). Backward elimination indicated an age-related decrease in mid-colonic propionate proportion and increase in mid- and distal colonic butyrate proportion (P<0.05), thereby modulating RS2 effects. In feces, increasing RS levels promoted fecal lactobacilli (R2=0.46; P<0.01) and bifidobacteria (R2=0.57; P<0.01), whereby the slope showed the need for a minimal RS level of 10% for a 0.5 log unit-increase in their abundance. Best-fit equations further supported that a longer experimental period increased fecal lactobacilli but decreased fecal bifidobacteria (P<0.05). In conclusion, dietary RS2 seems to effectively decrease digesta pH throughout the large intestine and increase lactic acid-producing bacteria in feces of pigs which may limit the growth of opportunistic pathogens in the hindgut. To achieve these physiologically relevant changes, dietary RS should surpass 10% to 15%.

Ferrite content measurement in super duplex stainless steel welds

Approaches to determining ferrite fraction (%) and ferrite number (FN) were examined for super duplex stainless steel (SDSS) welds. A reference sample was produced by bead-on-plate gas–tungsten arc welding of a type-2507 SDSS plate. By comparing different etchants and measurement practices, it was realized that etching with modified Beraha followed by computerized image analysis (IA) was the most accurate and quickest technique to measure ferrite fraction, which determined the same ferrite fraction (68.0 ± 2.6%) as that measured by electron diffraction backscattered analysis (67.6 ± 2.3%). A Round Robin test was performed on a reference sample at University West, Swerea KIMAB, Outokumpu Stainless, and Sandvik Materials Technology to investigate the repeatability of the technique. The ferrite fraction measurements performed at different laboratories showed very small variations, which were in the range of those seen when changing microscope in the same laboratory. After verification of the technique, the relationship between ferrite fraction and ferrite number (measured with FERITSCOPE®) was determined using 14 single (root) pass welds, including butt, corner, and T-, V-, and double V-joint geometries. The best-fit equation found in this study was ferrite number (FN) = 1.1 × ferrite fraction (%). To conclude, the ferrite fraction technique suggested in the present paper was accurate and repeatable, which made it possible to determine a ferrite fraction–ferrite number formula for SDSS single-pass welds.

Differences in the relation between bone mineral content and lean body mass according to gender and reproductive status by age ranges.

The present study aims: (1) to explore the influence of lean mass (LM) on bone mineral content (BMC), (2) to investigate the pubertal influences on the BMC-LM relation, and (3) to perform Z-score charts of BMC-LM relation, stratified by gender and reproductive status categorized by age ranges. A cross-sectional analysis was conducted using 4001 healthy subjects between 7 and 90years participating in the Health Workers Cohort Study. Of these, 720 participants were ≤ 19years, 2417 were women ≥ 20years, and 864 were men ≥ 20years. Using Dual X-ray absorptiometry (DXA), we measured BMC and LM. Participants' pubertal development was assessed according to Tanner's stage scale. To describe BMC-LM relation, simple correlation coefficients were computed. To produce best-fit equations, an ANOVA test was conducted. Z-score graphs for the BMC-LM relation were obtained. In general, the BMC-LM correlations were linear and highly significant. For boys, curves were virtually parallel, with similar intercepts and a progressive displacement of values toward the upper-right region of the graph, for each Tanner subgroup. For girls, curves for Tanner 1-2 and 4-5 stages were parallel; but, in girls Tanner 4-5, the intercepts were significantly higher by about +300-400g of BMC (P < 0.001). For postmenopausal women, the curve was parallel to that for the premenopausal but showed a lower intercept (P < 0.001). We provide DXA reference data on a well-characterized cohort of 4001 healthy subjects. These reference curves provide a reference value for the assessment and monitoring of bone health in all age groups included in the present study.

Henry's Law constant for CO2 in aqueous sodium chloride solutions at 1 atm and sub-zero (Celsius) temperatures

The solubility of CO2 in seawater is known to increase at colder temperatures, but few studies have examined the CO2 solubility in seawater and in sea-ice brines at sub-zero (Celsius) temperatures. The thermodynamic Henry's Law constant (KH) for CO2 in concentrated NaCl solutions was determined for the first time at sub-zero temperatures and salinities resembling those of the cryospheric seawater and sea-ice brine environments in polar and sub-polar oceans. The temperature (T, in Kelvin) dependence of the KH within the temperature and salinity ranges of this study (263 ≤ T ≤ 272 K and 35 ≤ S ≤ 152) is described by the following best-fit equation: ln KH = −2.484 + 2.775 × 10−2(274 − T) − 9.854 × 10−2/(274 − T) − 1.009 × 10−1 ln (274–T). The results show that the general practice, in geochemical and coupled climate‑carbon cycling models, of extrapolating KH values from above-zero to sub-zero temperatures underestimates the solubility of CO2 by up to 19%.

Packing density of mortar containing polypropylene, carbon or basalt fibres under dry and wet conditions

The addition of fibres to concrete can significantly improve the hardened properties but may adversely affect the fresh properties. Apart from entangling with each other to hinder the flow of fresh concrete, the fibres might also interfere with the packing of the solid particles in the concrete. However, the packing density of fibre reinforced concrete made with flexible fibres was rarely measured and thus the effects of flexible fibres on the packing density are still not well understood. Herein, the packing densities of mortar containing polypropylene, carbon or basalt fibres under dry and wet and with and without superplasticizer added conditions were measured and compared to evaluate the effects of the flexible fibres on the packing density. It was found that the packing density of mortar containing these fibres is much higher under wet condition than under dry condition and that the fibre content, fibre length and superplasticizer all have certain influences on the packing density. Based on the test results, best-fit equations revealing the variations of the packing density with the fibre factor under different conditions are derived.

Z Score Reference Ranges of Fetal Cardiothoracic Diameter Ratio.

This study aims to establish the z score reference ranges of cardiothoracic diameter ratio (CTR) of normal fetuses from 14 to 40 weeks' gestation. A cross-sectional study was conducted on low-risk singleton pregnancies with healthy fetuses. The CTR was performed using simple 2-dimensional sonography on the typical fetal 4-chamber view. The reference ranges were constructed according to gestational age (GA), biparietal diameter (BPD), and head circumference (HC) as independent variables based on the best-fit models, both mean and standard deviation (SD). A total of 683 fetuses were measured for CTR. The best-fit equations for the mean and SD as a function of GA, BPD, and HC are as follows: (1) CTR = 0.365 + 0.004 × GA in weeks (SD = 0.031 + 0.001 × GA); (2) CTR = 0.373 + 0.014 × BPD in cm (SD = 0.034 + 0.004 × BPD); and (3) CTR = 0.373 + 0.004 × HC in cm (SD = 0.032 + 0.001 × HC). The CTR was slightly increased with advanced GA, BPD, and HC. Complete nomograms with z score reference ranges of CTR were established throughout pregnancy. These nomograms may be useful to detect cardiac abnormalities.

Linkages between measures of biodiversity and community resilience in Pacific Island agroforests

Designing agroecosystems that are compatible with the conservation of biodiversity is a top conservation priority. However, the social variables that drive native biodiversity conservation in these systems are poorly understood. We devised a new approach to identify social-ecological linkages that affect conservation outcomes in agroecosystems and in social-ecological systems more broadly. We focused on coastal agroforests in Fiji, which, like agroforests across other small Pacific Islands, are critical to food security, contain much of the country's remaining lowland forests, and have rapidly declining levels of native biodiversity. We tested the relationships among social variables and native tree species richness in agroforests with structural equation models. The models were built with data from ecological and social surveys in 100 agroforests and associated households. The agroforests hosted 95 native tree species of which almost one-third were endemic. Fifty-eight percent of farms had at least one species considered threatened at the national or international level. The best-fit structural equation model (R2 = 47.8%) showed that social variables important for community resilience-local ecological knowledge, social network connectivity, and livelihood diversity-had direct and indirect positive effects on native tree species richness. Cash-crop intensification, a driver of biodiversity loss elsewhere, did not negatively affect native tree richness within parcels. Joining efforts to build community resilience, specifically by increasing livelihood diversity, local ecological knowledge, and social network connectivity, may help conservation agencies conserve the rapidly declining biodiversity in the region.

Determination and prediction of the digestible and metabolizable energy contents of corn germ meal in growing pigs.

ObjectiveThis experiment was conducted to determine the chemical composition, digestible energy (DE) and metabolizable energy (ME) contents of corn germ meals (CGM) and to develop equations to predict the corresponding energy contents based on the chemical characteristics of individual CGM.MethodsSixty-six barrows (initial body weight = 51.3±4.6 kg) were allotted to 11 diets including a basal diet and 10 CGM test diets in a completely randomized design. In the test diets, CGM was included in replacement of 30% of the energy-providing ingredients in the basal diet, resulting in a final inclusion rate of 29.1%. Each diet was fed to 6 barrows housed in individual metabolism crates for a 7-d acclimation period followed by a 5-d total but separate collection of feces and urine.ResultsConsiderable variation was observed in acid-hydrolyzed ether extract, ether extract, ash, calcium (Ca) and total phosphorus contents among the CGM samples. On dry matter (DM) basis, the DE and ME contents of the CGM ranged from 10.22 to 15.83 MJ/kg and from 9.94 to 15.43 MJ/kg, respectively. The acid detergent fiber (ADF) contents were negatively correlated with the DE and ME contents of CGM samples. The best-fit prediction equations for the DE and ME values (MJ/kg DM) of the 10 CGM were: DE = 26.85–0.28 insoluble dietary fiber (%)–17.79 Ca (%); ME = 21.05–0.43 ADF (%)–11.40 Ca (%).ConclusionThe chemical compositions of CGM vary depending on sources, particularly in ether extract and Ca. The DE and ME values of CGM can be predicted based on their chemical composition in growing pigs.

Transformational characteristics of ground-level ozone during high particulate events in urban area of Malaysia

Observations of ground-level ozone (O3), nitric oxide (NO), nitrogen dioxide (NO2), particulate matter (PM10) and meteorological parameter (temperature, relative humidity and wind speed) fluctuations during high particulate event (HPE) and non-HPE in Malaysia have been conducted for 2 years (2013 and 2014). The study focuses on urban areas, namely, Shah Alam, Petaling Jaya and Bandaraya Melaka. The diurnal variations of ground-level O3 concentration were higher during HPE than those during non-HPE in all urban areas. The concentration of O3 fluctuated more in 2014 than 2013 due to the higher incidences of HPE. Temperature and wind speed fluctuated with higher PM10, NO2 and NO concentrations during HPE than those during non-HPE in all urban sites. Relative humidity was lower during HPE than that during non-HPE. Positive correlations were found between PM10 and ozone during HPE for Shah Alam and Petaling Jaya with 0.81 and 0.79, respectively. Meanwhile, negative correlation (− 0.76) was recorded for Bandaraya Melaka. The non-HPE correlation of PM10 and O3 showed negative values for all locations except Petaling Jaya (0.02). Temperature and wind speed shows a strong positive correlation with ozone for all locations during HPE and non-HPE with the highest at Shah Alam (0.97). Inverse relationships were found between relative humidity and O3, in which the highest was for Shah Alam (− 0.96) in 2013 and Shah Alam (− 0.97) and Bandaraya Melaka (− 0.97) in 2014. The result of the ozone best-fit equation obtained an R2 of 0.6730. The study parameters had a significant positive relationship with the ozone predictions during HPE.

Reassessment of Resuspension Factor Following Radionuclide Dispersal: Toward a General-purpose Rate Constant.

A recent analysis of historical radionuclide resuspension datasets confirmed the general applicability of the Anspaugh and modified Anspaugh models of resuspension factors following both controlled and disastrous releases. While observations appear to have larger variance earlier in time, previous studies equally weighted the data for statistical fit calculations; this could induce a positive skewing of resuspension coefficients in the early time-period. A refitting is performed using a relative instrumental weighting of the observations. Measurements within a 3-d window are grouped into singular sample sets to construct standard deviations. The resulting best-fit equations produce tamer exponentials, which give decreased integrated resuspension factor values relative to those reported by Anspaugh. As expected, the fits attenuate greater error among the data at earlier time. The reevaluation provides a sharper contrast between the empirical models and reaffirms their deficiencies in the short-lived timeframe wherein the dynamics of particulate dispersion dominate the resuspension process.

Investigating Relationships between Engineering Properties of Various Rock Types

In the literature on rock mechanics several authors have proposed different constants and empirical equations for the physical and mechanical properties of various rock types. This is because researchers usually base their results on the limited number of test samples and/or lithological units. The research presented here has been primarily performed to solve this variation problem. It makes sense to have a general expression for all types of rocks. To accomplish this, a considerable amount of data comprising 4,991 datasets was collected through an extensive literature review. The results were statistically analyzed to determine the range, mean, standard deviation for each investigated rock property. The physical and mechanical properties of the rocks were also plotted against each other in order to estimate one property from the other. The correlation coefficients and best-fit equations were determined by the least squares curve fit method. Usually good correlations were found between index tests, and physico-mechanical properties. At the end, various regression equations are proposed particularly applicable to the whole rock types.

Establishing normal values for pediatric nighttime sleep measured by actigraphy: a systematic review and meta-analysis.

Despite the widespread use of actigraphy in pediatric sleep studies, there are currently no age-related normative data. To systematically review the literature, calculate pooled mean estimates of actigraphy-derived pediatric nighttime sleep variables and to examine the magnitude of change with age. A systematic search was performed across eight databases of studies that included at least one actigraphy sleep variable from healthy children aged 0-18 years. Data suitable for meta-analysis were confined to ages 3-18 years with seven actigraphy variables analyzed using random effects meta-analysis and meta-regression performed using age as a covariate. In total, 1334 articles did not meet inclusion criteria; 87 had data suitable for review and 79 were suitable for meta-analysis. Pooled mean estimates for overnight sleep duration declined from 9.68 hours (3-5 years age band) to 8.98, 8.85, 8.05, and 7.4 for age bands 6-8, 9-11, 12-14, and 15-18 years, respectively. For continuous data, the best-fit (R2 = 0.74) equation for hours over the 0-18 years age range was 9.02 - 1.04 × [(age/10)^2 - 0.83]. There was a significant curvilinear association between both sleep onset and offset with age (p < .001). Sleep latency was stable at 19.4 min per night. There were significant differences among the older age groups between weekday and weekend/nonschool days (18 studies). Total sleep time in 15-18 years old was 56 min longer, and sleep onset and offset almost 1 and 2 hours later, respectively, on weekend or nonschool days. These normative values have potential application to assist the interpretation of actigraphy measures from nighttime recordings across the pediatric age range, and aid future research.

Quantification of the Learning Curve for Arthroscopic Os Trigonum Excision

The purpose of the present study was to quantify the learning curve for arthroscopic os trigonum excision using the log-linear model. Twenty-three consecutive feet underwent arthroscopic os trigonum excision and release of the flexor hallucis longus. The required time from the beginning of shaving of the soft tissue until completion of os trigonum excision and release of the flexor hallucis longus (van Dijk time) was recorded. Regression analysis was applied to predict the required time on the basis of the cumulative case volume after logarithmic transformation of both statistics. The mean required time was 35.2 (range 9 to 90) minutes. After logarithmic transformation, a significant linear correlation was observed between the required time and the cumulative case volume (p = .0043). The best-fit linear equation was calculated as log (y, estimated required time) = −0.41 log (x, case volume) + 1.86, resulting in an estimated learning rate of 75.3% (= 2−0.41). The results showed an overall time reduction in arthroscopic os trigonum excision in support of a learning curve effect with an ~75% learning rate, indicating that the required time for arthroscopic os trigonum excision can decrease by ≤25% when the cumulative volume of cases has doubled.

Application of eggshell wastes for boron remediation from water

Boron in high concentration levels leads to harmful effects on the environment and human health. Hence, it needs to be eliminated from desalinated water in order to improve water quality. As a result, the removal of boron from aqueous solution using waste eggshell as an adsorbent was investigated. Eggshell, as an agricultural waste, was studied as they are low cost and environmentally friendly, where the presence of calcium carbonate makes it an effective sorbent. The percent removal capacity of boron was studied under various experimental conditions including pH, initial boron concentration and temperature. Surface characterization, morphology and functional groups on the external surface of the adsorbent were investigated using Fourier transform infrared (FTIR) and scanning electron microscopy (SEM). FTIR showed that the main functional groups were CO and CaO on the surface of the eggshells, and SEM indicated changes in surface morphology where well-defined structure was observed after calcination. However, after adsorption of boron, no significant morphology changes were detected. Langmuir, Freundlich, Dubinin-Radushkevich and Temkin isotherm models were used to determine the best-fit equation to represent the experimental data. Results showed that removal efficiency of boron was 96.3% at pH6, and the adsorption processes for both waste eggshell and calcined eggshell were exothermic and spontaneous.

DEM simulations: mixing of dry and wet granular material with different contact angles

In solid mixing the raw materials typically differ at least in one material property, such as particle size, solid density and wetting properties, which in turn influence particle mobility. For example, smaller particles can percolate through the voids of larger ones under the influence of strain and gravity. This may produce fine particle accumulation at the bottom of the mixing vessel which results in undesired, inhomogeneous final products. When wet particles with different wetting properties need to be mixed, heteroagglomeration may occur as another segregation mechanism. We present a new capillary bridge force model to study segregation in moist cohesive mixing processes using DEM. New analytical equations of best fit are derived by solving the Young–Laplace equation and performing a regression analysis, in order to investigate discontinuous mixing processes of dry and moist materials with different particle sizes and different contact angles. Compared to a dry mixing process, mixing efficiency is improved by the addition of a small amount of liquid. While percolating segregation is reduced, heteroagglomerates occur in the wet mixing process.

Nitrogen-corrected apparent metabolizable energy value of corn distillers dried grains with solubles for laying hens

The purpose of this study was to determine the nutrient composition and AMEn content of corn distillers dried grains with solubles (DDGS) to develop prediction equations for AMEn in laying hens. Ten samples of DDGS ranging in ether extract (EE) from 21.8 to 177.8 g/kg (DM basis) were selected and were subsequently fed to laying hens to determine AMEn content. A total of 176 62-week-old laying hens (Lohmann-Pink) were placed in metabolic cages (2 hens/cage) and were allotted into 11 dietary treatments (8 cages per treatment) according to hen-day egg production. Dietary treatments included a corn-soybean meal reference diet and 10 test diets. Each test diet was created by mixing the reference diet with 200 g/kg one of 10 DDGS samples at the expense of the energy-yielding ingredients (139.6 g/kg corn, 59.0 g/kg soybean meal, and 1.4 g/kg rapeseed oil).Experimental diets were fed in the 7-day adaptation period, followed by the 4-day total excreta collection period. Gross energy (GE) and crude protein (CP) of the experimental diets and excreta were determined to calculate AMEn for each DDGS sample. On the DM basis, AMEn of the 10 corn DDGS samples ranged from 729 to 2535 kcal/kg. Analyses were conducted to determine the GE, CP, EE, DM, crude fiber, neutral detergent fiber (NDF), acid detergent fiber (ADF), and ash content of the DDGS samples. Stepwise regression resulted in the following best-fit equation for AMEn (DM basis) based on the coefficient of determination, SE, and the Mallows’ statistic (Cp): AMEn, kcal/kg = 0.777 × GE (kcal/kg) − 5.39 × NDF (g/kg) (R2 = 0.99; SE = 172; Cp = −3.37). These results suggested that the composition of corn DDGS may be used to predict AMEn in laying hens.