Generalization of the Dubovitzky-Milutyn optimality conditions

Various types of conical approximation of sets are discussed. The notions of an external cone and an internal cone result in a strengthened separation theorem. Based on this theorem, some generalizations of the Dubovitzky-Milutyn optimality conditions are given.This research was sponsored by the Institute of Automatic Control, Department of Electronics, Technical University, Warsaw, Poland.     

Strain determination in bone sections with simultaneous 3D digital holographic interferometry

A 3D digital holographic interferometer was used to measure the surface strain components in two different bovine׳s bone sections. The applied force on the sample was induced by a precisely controlled lateral micro compression. The simultaneous acquisition capability of the system helps to record a fast sequence of images, each one containing three independent holograms that result in three orthogonal displacement components u, v and w from which the surface strain components ɛ_x, ɛ_y and γ_xy over the bone׳s field of view were calculated. This research study was carried out in two different bone sections: the cortical bone and the medullary cavity/yellow marrow section. The resulting strain concentrators are of great importance to better understand the mechanical response of complex biological structures such as this bovine femoral bone.     

Observer theory

The paper is devoted to a comprehensive exposition of the theory of partial state observers in the state space context and the elucidation of the connection between this theory and the theory of observers in the behavioral context, as developed in Valcher and Willems [1999]. For this we use several techniques, including geometric control theory, polynomial and rational models, shift realizations, coprime factorizations, partial realizations and the basic results on behaviors and behavior homomorphisms. A connection between observers and the construction of state maps is made.     

Accurate determination of arsenic in arsenobetaine standard solutions of BCR-626 and NMIJ CRM 7901-a by neutron activation analysis coupled with internal standard method

Neutron activation analysis (NAA) coupled with an internal standard method was applied for the determination of As in the certified reference material (CRM) of arsenobetaine (AB) standard solutions to verify their certified values. Gold was used as an internal standard to compensate for the difference of the neutron exposure in an irradiation capsule and to improve the sample-to-sample repeatability. Application of the internal standard method significantly improved linearity of the calibration curve up to 1 μg of As, too. The analytical reliability of the proposed method was evaluated by k₀-standardization NAA. The analytical results of As in AB standard solutions of BCR-626 and NMIJ CRM 7901-a were (499 ± 55) mg kg⁻¹ (k = 2) and (10.16 ± 0.15) mg kg⁻¹ (k = 2), respectively. These values were found to be 15-20% higher than the certified values. The between-bottle variation of BCR-626 was much larger than the expanded uncertainty of the certified value, although that of NMIJ CRM 7901-a was almost negligible.     

取向模压成型技术增强聚乳酸力学性能的研究

以取向模压成型制备了聚l -乳酸、聚dl -乳酸骨折内固定棒 (Φ =3 .2mm)。与通常的熔融成型相比 ,新的成型技术可以成倍地提高内固定材料的初始力学强度 ,其中聚l -乳酸棒的弯曲强度达 2 63±1 1MPa,聚 dl-乳酸棒的弯曲强度达 1 72± 4MPa。SEM观察显示取向后聚 l-乳酸棒的纵向纤化程度高 ,冲击断面有大量纤维尾端 ;取向后聚dl -乳酸棒弯曲断裂时呈韧性断裂。而熔融模压成型的聚l -乳酸及聚dl -乳酸棒弯曲断裂时呈脆性断裂特征。     

Analysis of human breath with micro extraction techniques and continuous monitoring of carbon dioxide concentration

The detection of volatile organic compounds (VOCs) in human breath can be useful for the clinical routine diagnosis of several diseases in a non-invasive manner. Traditional methods of breath analysis have some major technical problems and limitations. Membrane extraction with a sorbent interface (MESI), however, has many advantages over current methods, including good selectivity and sensitivity, and is well suited for breath analysis. The aim of this project was to develop a simple and reproducible sampling device and method based on the MESI system for breath analysis. The feasibility and validity of the MESI system was tested with real human breath samples. Internal standard calibration methods were used for the quantitative analysis of various breath samples. Calibration curves for some main components (target analytes such as acetone and pentane) were determined in the research. The optimized stripping-side and feeding-side gas velocities were determined. The use of breath CO₂ as an internal standard for the analysis of breath VOCs is an effective method to solve the difficulties associated with variations in the target analyte concentrations in a sample, which are attributed to mass losses and different breathing patterns of different subjects. In this study, the concentration of breath acetone was successfully expressed normalized to CO₂ as in the alveolar air. Breath acetone of healthy males and females profiled at different times of the day was plotted using the MESI system, and results were consistent with the literature. This technique can be used for monitoring breath acetone concentrations of diabetic patients and for applications with other biomarker monitoring.     

Fast high-throughput method for the determination of acidity constants by capillary electrophoresis: I. Monoprotic weak acids and bases

A new and fast method to determine acidity constants of monoprotic weak acids and bases by capillary zone electrophoresis based on the use of an internal standard (compound of similar nature and acidity constant as the analyte) has been developed. This method requires only two electrophoretic runs for the determination of an acidity constant: a first one at a pH where both analyte and internal standard are totally ionized, and a second one at another pH where both are partially ionized. Furthermore, the method is not pH dependent, so an accurate measure of the pH of the buffer solutions is not needed. The acidity constants of several phenols and amines have been measured using internal standards of known pK_a, obtaining a mean deviation of 0.05 pH units compared to the literature values.     

Ion-Ion and Ion-Solvent Interactions of Tetraalkyl Ammonium Bromide in Mixed DMF-Water Systems at Different Temperatures

Density (ρ), viscosity (η) and ultrasonic velocity (U) of tetraethylammonium bromide (TEAB) and tetrapropylammonium bromide (TPAB) in 10, 20 and 30% of N,N-dimethylformamide (DMF) and water mixtures have been measured as a function of electrolyte concentration at 303, 308 and 313 K. The experimental values of ρ,η and U are used to calculate free volume (V _f), internal pressure (π _i), solvation number (S _n) and viscosity B-coefficient. These parameters are used to discuss the ion-solvent and ion-ion interactions and structure making tendency of the electrolyte.