Binary diffractive beam splitters with arbitrary diffraction angles

Diffractive optical beam splitters designed with iterative Fourier transform type algorithms can produce only certain diffraction angles given by the spatial frequencies used for the computations, which are multiples of a certain base spatial frequency. We have developed a design algorithm that overcomes this limitation and can be used to compute binary diffractive elements with arbitrary diffraction angles. The simulated and experimentally measured properties of optical elements producing beam arrays in circular arrangements are presented and discussed.     

Entropy in linear programs

This paper treats entropy constrained linear programs from modelling as well as computational aspects. The optimal solutions to linear programs with one additional entropy constraint are expressed in terms of Lagrange-multipliers. Conditions for uniqueness are given. Sensitivity and duality are studied. The Newton—Kantorovich method is used to obtain a locally convergent iterative procedure. Related problems based on maximum entropy or minimum information are discussed.     

Test of the isotropy of the speed of light using a continuously rotating optical resonator

We report on a test of Lorentz invariance performed by comparing the resonance frequencies of one stationary optical resonator and one continuously rotating on a precision air bearing turntable. Special attention is paid to the control of rotation induced systematic effects. Within the photon sector of the standard model extension, we obtain improved limits on combinations of 8 parameters at a level of a few parts in 10(-16). For the previously least well known parameter we find [EQUATION: SEE TEXT]. Within the Robertson-Mansouri-Sexl test theory, our measurement restricts the isotropy violation parameter [EQUATION: SEE TEXT]. corresponding to an eightfold improvement with respect to previous nonrotating measurements.     

Evaluation of process parameters of ultrasonic treatment of bacterial suspensions in a pilot scale water disinfection system

In this study, several process parameters that may contribute to the efficiency of ultrasound disinfection are examined on a pilot scale water disinfection system that mimics realistic circumstances as encountered in an industrial environment. The main parameters of sonication are: (i) power; (ii) duration of treatment; (iii) volume of the treated sample. The specific energy (E_s) is an indicator of the intensity of the ultrasound treatment because it incorporates the transferred power, the duration of sonication and the treated volume. In this study, the importance of this parameter for the disinfection efficiency was assessed through changes in volume of treated water, water flow rate and electrical power of the ultrasonic reactor. In addition, the influences of the initial bacterial concentration on the disinfection efficiency were examined. The disinfection efficiency of the ultrasonic technique was scored on a homogenous and on a mixed bacterial culture suspended in water with two different types of ultrasonic reactors (Telsonic and Bandelin). This study demonstrates that specific energy, treatment time of water with ultrasound and number of passages through the ultrasonic reactor are crucial influential parameters of ultrasonic disinfection of contaminated water in a pilot scale water disinfection system. The promising results obtained in this study on a pilot scale water disinfection system indicate the possible application of ultrasound technology to reduce bacterial contamination in recirculating process water to an acceptable low level. However, the energy demand of the ultrasound equipment is rather high and therefore it may be advantageous to apply ultrasound in combination with another treatment.     

Methane dissociation on Ni(111): the role of lattice reconstruction

The effects of lattice motion and reconstruction on the dissociation of methane on Ni(111) are explored, using both electronic structure theory and quantum dynamical calculations. We show that during the reaction, the Ni lattice reconstructs, effectively lowering the barrier to reaction, in contrast with earlier models of this process.     

Soluble Congeners of Prior Insoluble Shape-Persistent Imine Cages

One of the most applied reaction types to synthesize shape-persistent organic cage compounds is the imine condensation reaction and it is assumed that the formed cages are thermodynamically controlled products due to the reversibility of the imine condensation. However, most of the synthesized imine cages reported are formed as precipitate from the reaction mixture and therefore rather may be kinetically controlled products. There are even examples in literature, where resulting cages are not soluble at all in common organic solvents to characterize or study their formation by NMR spectroscopy in solution. Here, a triptycene triamine containing three solubilizing n-hexyloxy chains has been used to synthesize soluble congeners of prior insoluble cages. This allowed us to study the formation as well as the reversibility of cage formation in solution by investigating exchange of building blocks between the cages and deuterated derivatives thereof.     

Totally Splittable Polytopes

A split of a polytope is a (necessarily regular) subdivision with exactly two maximal cells. A polytope is totally splittable if each triangulation (without additional vertices) is a common refinement of splits. This paper establishes a complete classification of the totally splittable polytopes.