Types of likelihood maxima in mixture models and their implication on the performance of tests

In two-component mixtures of exponential distributions, different strategies for starting the likelihood maximization algorithm converge to different types of maxima. The power of an LR test of homogeneity against such a mixture strongly depends on the considered strategy, and global maximization need not result in the largest power. An explanation is given on basis of a systematic investigation of the likelihood function in a large number of simulations, using a variety of diagnostic tools. Thereby, we also gain a deeper insight into the properties of the samples that generate particular types of solutions of the likelihood equation. In particular, “spurious solutions” often occur; these are mainly responsible for the fact that global maximization may not result in a statistically meaningful estimator. Removing the smallest elements of a sample may drastically increase the power of previously inferior strategies. This research has been supported by a grant from the Deutsche Forschungsgemeinschaft.     

Recent advances in electrochemical analysis of biomacromolecules. Catalytic hydrogen evolution and modification of glycoproteins and glycans by Os(VI) complexes

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A study of the stability of pyrimidine series cytostatics,Ftorafur and 5-fluorouracil: The effect of oxidation on the stability of Ftorafur and 5-fluorouracil

The stability of 1% solutions of cytostatics Ftorafur and 5-fluorouracil was studied during oxidation with hydrogen peroxide in alkaline (0.1 N NaOH), acidic (0.1 N H₂SO₄), and weakly acidic (pH 5) solutions by thin-layer chromatography. The decrease in the cytostatic content was monitored spectrophotometrically in the uv region. The greatest decrease in the cytostatic content occurred in alkaline solutions, where the pyrimidine ring opened between N3 and C4 and between C6 and N1, with formation of urea.     

L-Prolinamide Catalyzed Aqueous Direct Aldol Reaction： an Environment-friendly Method for the Synthesis of β- Hydroxyl keto nes

An environment-friendly L-prolinamide catalyzed aldol reaction has been developed. The reaction exhibited broad substrate generality, and high yields with good diastereoselectivity were obtained for cyclic ketones.The simplicity of product isolation, usage of water as environmentally benign reaction medium, and the usage of cheap, readily available and recyclable catalyst make this process promising to be developed for large-scale preparation of β-hydroxyl ketones.     

Extraction of Alkylphenols and Nonylphenol Mono- and Diethoxylates from Water Using Magnetically Modified Adsorbents

An LC-DAD-ESI-MS⁽²⁾ method was developed for simultaneous analysis of major chemical constituents in Shexiang Baoxin Pill (SBP), an important multiherbal formula in traditional Chinese medicine widely used for treating cardiovascular diseases. The chromatographic separation was performed on a Symmetry C₁₈ column (5 μm, 250 × 4.6 mm), whilst water with 0.5% formic acid and acetonitrile were used as mobile phase. On the basis of the characteristic UV absorption profile, the information of molecular weight and structure provided by ESI-MS⁽²⁾, 57 constituents from moschus, radix rhizoma ginseng, calculus bovis, cortex cinnamomi, styrax and venenum bufonis, were detected and 47 of them were identified in this study. The method can be the basis for the quality control of SBP.     

Supramolecular Fe3O4@PEG/−diaza crown ether@Ni: a novel magnetically reusable nano catalyst for the clean synthesis of 2‐aryl‐2,3‐dihydroquinazolin‐4(1H)‐ones

Ni@diaza crown ether complex supported on magnetic nanoparticle was provided by grafting technique. The catalytic activity of Fe₃O₄@diaza crown ether@Ni was explored through one‐pot synthesis of 2,3‐dihydroquinazolin‐4(1H)‐ones and it was used as an efficient and recoverably constant nanocatalyst. FT‐IR, SEM, TEM, XRD, BET, ICP, EDS, and TGA techniques were employed to specify the nanocatalyst. This heterogeneous catalyst demonstrated acceptable recyclability and could be used again several times with no considerable loss of its catalytic activity.     

Fe3O4@silica‐MCM‐41@DABCO: A novel magnetically reusable nanostructured catalyst for clean in situ synthesis of substituted 2‐aminodihydropyrano[3,2‐b]pyran‐3‐cyano

DABCO (1,4‐diazabicyclo[2.2.2]octane)‐modified magnetite with silica‐MCM‐41 shell (Fe₃O₄@silica‐MCM‐41@DABCO) as an effective, magnetic and novel heterogeneous reusable nanocatalyst was synthesized and analysed using various techniques. Evaluation of the catalytic activity of this nanocatalyst was performed in the clean synthesis of substituted 2‐aminodihydropyrano[3,2‐b]pyran‐3‐cyano in high yields via in situ reaction of azido kojic acid, malononitrile and various aldehydes.     

Real-life curriculum-based timetabling with elective courses and course sections

This paper presents an innovative approach to curriculum-based timetabling. To capture complex relations of real life curriculum-based timetabling problems, curricula are defined by a rich model that includes optional courses and course groups among which students are expected to take a subset of courses. In addition, courses may contain alternative course sections. A transformation between the proposed curriculum model and student course enrollments is formalized and a local search algorithm generating corresponding enrollments is introduced. While the proposed curriculum model is too complicated for existing curriculum-based solvers, the transformation enables curriculum-based timetabling in any existing enrollment-based course timetabling solver. The approach was implemented in a well established enrollment-based course timetabling system UniTime. The system has been successfully applied in practice at the Faculty of Education at Masaryk University for about 7,500 students and 260 curricula and at the Faculty of Sports Studies at Masaryk University for about 1,400 students and 25 curricula. Experimental results related with these problems are demonstrated for two semesters.