Syntheses,Spectral, Thermal and Structural Characterization of 2‐Phenyl‐2‐(1‐hydroxyiminoethyl)‐1,2,3,4‐tetrahydroquinazoline and Its Novel Nickel(II) Complex

The 2‐phenyl‐2‐(1‐hydroxyiminoethyl)‐1,2,3,4‐tetrahydroquinazoline (HL) and its Ni^II complex have been prepared and characterized by spectral method (FT‐IR, NMR (¹³C and ¹H), UV‐vis.), elemental analysis, magnetic susceptibility and thermal analysis (TG, DTA) techniques. The crystal structures of HL and Ni^II complex were also determined by the single crystal X‐ray diffraction. The HL and Ni^II complex crystallizes in the monoclinic and triclinic, space groups P2₁/c and , respectively. The complex was occurred by the elimination of 1 mole of 2‐aminobenzylamine from the 2 moles of the HL after the ring opening reaction by the Ni^II attack. Crystallographic study reveal that Ni^II atom has a square planer geometry being coordinated by four nitrogen atoms of HL. Two thermal processes of the HL and Ni^II complex can occur in TG and DTA curves.     

Synthesis of poly(2-acetamidoacrylic acid) and its PEGMA block copolymer via ATRP in water

Controlled polymerization of a captodative monomer, 2-acetamidoacrylic acid (AAA), was studied for the first time in the literature. Salt of the monomer in water was polymerized using ATRP method and influence of several factors, including solvent composition, halogen exchange and additives like pyridine and halide salts were investigated to improve the control. Captodative monomers form very stable radicals favoring the active species over the dormant one. Depolymerization at room temperature under ATRP conditions was determined as the major obstacle in front of the high molecular weight polymers and block copolymer formation. Nevertheless, poly(AAA-b-(AAA-co-PEGMA)) block polymers were prepared through ATRP and possible applications were discussed. As an example, pH responsive nature and ability to coat superparamagnetic iron oxide nanoparticles were demonstrated.     

Instability of FIFO in a simple queueing system with arbitrarily low loads

We show, using a simple example, that the First-In-First-Out (FIFO) policy can be unstable in a system with arbitrarily low load. Our proof is based on the observation that the special structure of the example we use allows us to establish stability using a much simpler queueing system.     

Fine and hyperfine structure in the atomic spectrum of niobium

A parametric analysis of the fine and the magnetic dipole hyperfine structure for the three configurations of odd parity 4d³5s5p, 4d⁴5p and 4d²5s²5p was performed. Effective one-electron parameters were determined and theoretical predictions are given for the magnetic dipole hyperfine structure constants A for the levels of these three configurations. Additionally, 12 new energy levels could be found, four of odd and eight of even parity, by re-analysing data for experimental wavelengths of Nb.     

Determination of cadmium, chromium, copper and lead in sediments and soil samples by electrothermal atomic absorption spectrometry using zirconium containing chemical modifiers.

A method for direct determination of cadmium, chromium, copper and lead in sediments and soil samples by electrothermal atomic absorption spectrometry using Zr, Ir, etylenediamine acetic acid (EDTA), Zr + EDTA, Ir + EDTA, Zr + Ir and Zr + Ir + EDTA as chemical modifiers in 0.5% (v/v) Triton X-100 plus 0.2% (v/v) nitric acid mixture used as diluent was developed. The effects of mass and mass ratio of modifiers on analytes in sample solutions were studied. The optimum masses and mass ratios of modifiers: 20 microg of Zr, 4 microg of Ir, 100 microg of EDTA and 20 microg of Zr + 4 microg of Ir + 100 microg of EDTA, were used to enhance the analyte signals. Pyrolysis and atomization temperatures, atomization and background absorption profiles, characteristic masses, and detection limits of analytes in samples were compared in the presence or absence of a modifier. The detection limits and characteristic masses of analytes in a 0.5% (m/v) dissolved sample (dilution factor of 200 ml g(-1)) obtained with Zr + Ir + EDTA are 8.0 ng g(-1) and 1.2 pg for Cd, 61 ng g(-1) and 4.3 pg for Cr, 32 ng g(-1) and 23 pg for Cu, and 3.4 ng g(-1) and 19 pg for Pb, respectively. The Zr + Ir + EDTA modifier mixture was found to be preferable for the determination of analytes in sediment and soil-certified and standard reference materials. Depending on the sample type, the percent recoveries of analytes were increased from 81 to 103% by using the proposed modifier mixture; the results obtained are in good agreement with the certified values.     

The End Results of General Relativity Theory Via Just Energy Conservation and Quantum Mechanics

Herein we present a whole new approach that leads to the end results of the general theory of relativity via just the law of conservation of energy (broadened to embody the mass and energy equivalence of the special theory of relativity) and quantum mechanics. We start with the following postulate. Postulate: The rest mass of an object bound to a celestial body amounts less than its rest mass measured in empty space, and this, as much as its binding energy vis-á-vis the gravitational field of concern.     

Maßgeschneiderter optischer Raum. Transformationsoptik

Die Transformationsoptik erlaubt Verformungen des optischen Raums, die denen der Raumzeit in der Allgemeinen Relativitätstheorie bei Anwesenheit von Materie ähneln. Von Fata Morganas ist der Effekt kontinuierlich veränderlicher Brechzahlprofile vertraut. Doch erst die Theorie der Transformationsoptik erlaubt die systematische Entwicklung völlig neuer optischer Funktionen. Computersimulationen des Karlsruhe Institute of Technology zeigen, wie eine Tarnkappe und eine kugelförmige Strahlumlenkung funktionieren könnten – zwei Beispiele für die ungeahnten prinzipiellen Möglichkeiten der Transformationsoptik. Die experimentelle Umsetzung im optischen Spektralbereich stellt allerdings noch eine große Herausforderung dar.     

Elliptic open books on torus bundles over the circle

As an application of the construction of open books on plumbed 3-manifolds, we construct elliptic open books on torus bundles over the circle. In certain cases these open books are compatible with Stein fillable contact structures and have minimal genus.      

Experimental and analytical investigation of the mechanics of crawl stroke swimming

A three dimensional analytical model for crawl stroke swimming is developed in which the swimmer is modeled as a body and two arms connected to the body at the shoulder joints. Each arm is assumed to consist of three segments. The numerical results obtained from the model are compared with the results of two sets of experiments performed. In the first series of experiments, the tether forces developed in crawl stroke swimming are measured and a linear correlation between the tether force and the stroke rate is obtained. In the second series of experiments, untethered crawl stroke swimming for different arm position angles is recorded. The results are presented in graphical forms and the effect of stroke rate on swimming velocity is discussed.