13 research outputs found
The effect of corn grain micronization on diet digestibility and blood biochemical parameters in weaned Holstein calves
Aim of study: To evaluate corn grain micronization for calves fed a grower diet. Area of study: Padinska Skela – Belgrade, Serbia. Material and methods: Thirty weaned Holstein dairy calves (65–74 days of age) were randomly assigned to one of two treatments with growers containing micronized (MCG) or untreated corn grain (UCG). The experimental period lasted for 60 days. Main results: The values of total tract apparent digestibility of dry matter (DM), organic matter (OM), crude protein (CP), and nonfiber carbohydrates (NFC) were higher for calves fed MCG versus those within the UCG treatment by 3.9% (p<0.05), 7.0% (p<0.01), 7.1% (p<0.01) and 7.5% (p<0.05), respectively, for the days 25–30 of the experimental period. In addition, the values of digestibility of OM, CP, and NFC were higher by 4.9% (p<0.05), 5.7% (p<0.05), and 6.0% (p<0.05), respectively, for the days 55–60 of the experimental period. The density of metabolizable energy, net energy for maintenance and gain in consumed dietary DM was higher (p<0.001) by 4.7, 5.5, and 7.2%, respectively for calves fed on the grower containing micronized corn grain (MCG), during the first digestibility period, and by 3.0, 3.6, and 4.6%, respectively, during the second digestibility period. Energy intake was lower (p<0.05) during the second digestibility period, for calves fed a diet with micronized corn. Blood urea N was affected (p<0.001) by dietary treatments. Lower values (10.2%) were observed for calves fed the grower containing MCG. Research highlights: The micronization of corn grain is a useful tool for optimizing weaned calf production due to the improvement in the digestibility and energy content of the ration. © 2023 CSIC
Analysis of the brachistochronic motion of a variable mass nonholonomic mechanical system
The paper considers the brachistochronic motion of a variable mass nonholonomic mechanical system [3] in a horizontal plane, between two specified positions. Variable mass particles are interconnected by a lightweight mechanism of the 'pitchfork' type. The law of the time-rate of mass variation of the particles, as well as relative velocities of the expelled particles, as a function of time, are known. Differential equations of motion, where the reactions of nonholonomic constraints and control forces figure, are created based on the general theorems of dynamics of a variable mass mechanical system [5]. The formulated brachistochrone problem, with adequately chosen quantities of state, is solved, in this case, as the simplest task of optimal control by applying Pontryagin's maximum principle [1]. A corresponding two-point boundary value problem (TPBVP) of the system of ordinary nonlinear differential equations is obtained, which, in a general case, has to be numerically solved [2]. On the basis of thus obtained brachistochronic motion, the active control forces, along with the reactions of nonholonomic constraints, are determined. The analysis of the brachistochronic motion for different values of the initial position of a variable mass particle B is presented. Also, the interval of values of the initial position of a variable mass particle B, for which there are the TPBVP solutions, is determined
Prism design for scanning applications and illumination of microscopy sample
There is disclosed a prism used for scanning applications such as total internal reflection microscopy in which the prism is translated relative to an incident light beam. A geometry is disclosed which cancels walk of the beam footprint at the base of the prism. Walk of the beam due to irregularities in a largely planar sample surface located at the prism base are cancelled by coupling movement of the incident beam to movement of the sample in the field of view of the objective lens, for example as part of a autofocus arrangement