Diocotron instability of the electron beam in the drift tube of a gyrotron

A cold fluid model is used to investigate instabilities associated with a velocity shear due to the self fields of a relativistic electron beam inside the beam tunnel of a gyrotron. General statements concerning the stability of an electron beam like the frequency and the growth rate are possible. The growth is expressed as a length that can be compared with the geometry in the gun-tube-resonator system.     

Absolute fixed point sets for continuum-valued maps

The notion of an absolute fixed point set in the setting of continuum-valued maps will be defined and characterized.

     

An atom efficient and solvent-free synthesis of structurally diverse amides using microwaves

An array of structurally diverse amides was synthesized efficiently by combining (primary and secondary) amines and carboxylic acids in one-pot under solvent-free microwave (MW) conditions. In most cases, no racemization was observed with optically active inputs and chiral amides were obtained in high ee or de.     

CAS in general mathematics education

A rational discussion of the use of Computer algebra systems (CAS) in mathematics teaching in general education needs an explicit image of (general) mathematics education, an explication of global perspectives and goals on mathematics teaching focusing on general education (chapter 1). The conception of general education according to the «ability of communication with experts» described in chapter 2 can be such an orientation for analysing, considering, classifying and assessing the didactical possibilities of using CAS. CAS are materialised mathematics allowing for more or less exhaustive outsourcing of operative (also symbolically) knowledge and skills to the machine. This frees up space of time as well as mental space for the development of those competences being in our view relevant for general mathematics education. In chapter 3 the idea of outsourcing and the role of CAS for it is discussed more detailed as well as consequences being possible for the CAS-supported teaching of mathematics. Beyond, CAS can be didactically used and reflected as a model of communication between (mathematical) experts and lay-persons (chapter 4). Chapter 5 outlines some research perspectives.     

Rosafluin,ein neues Diapocarotindiol aus Rosenblüten. 8. Mitteilung über Rosenfarbstoffe

Rosafluine, a Novel Diapocarotenediol from Rose Petals A strongly fluorescent trace compound from rose petals was identified as the as yet unknown 10,10′-diapocarotene-10,10′-diol ( = 4,9-dimethyldodeca-2,4,6,8,10-pentaene-1,12-diol; 2 ).     

Synthetic Membrane Technology Sessions,Instrumentation Symposium

When a protein is exposed to a ligand linked to a water soluble polymer, a macrocomplex can be formed that can be isolated from the contaminant medium by different methods such as affinity partitioning or gel filtration. Ultrafiltration technique has also been tested in the separation of trypsin and chymotrypsin using a high molecular weight dextran—p-aminobenzamidine as a macroligand. Some theoretical considerations are given in order to evaluate the performance that can be expected from this biospecific complexation—ultrafiltration technique in the separation of biological species.     

Solvent-free methylthiomethyllithium [LiCH2SMe]infinity: solid state structure and thermal decomposition

Solvent-free [LiCH2SMe]infinity forms a layer structure consisting of four- (Li2C2), five- (Li2CS2), and six-membered (Li2C2S2) rings in the solid state; the compound violently explodes upon heating to T=160+/-5 degrees C under an argon atmosphere.     

Low noise broadband modulated preamplifiers for a variety of transducers

Often, increases in signal-to-noise ratio and basic sensitivity are gained by the use of carrier modulation. Further advantage can be taken of this process by the use of varactors. These are suitably biased solid-state diodes and transistors, usually used to provide capacitance reactances. Their capacitance is changed by applying a voltage. The change in capacitance available by applying to their terminals the electrical output of a transducer—such as many of the sensors for light, heat, sound, mechanical stress and deformation—can be used in suitable modulating circuits. The magnitudes of reactance available from varactors fall conveniently into the range of values suitable for the carrier frequencies now accessible by means of another stable, mass produced solid-state device, the crystal clock oscillator.In general, the complexity of the carrier circuit to be chosen depends upon the sensitivity and noise floor requirements. This paper describes circuits for applying the modulation process, and discusses the hierarchy of choices for the methods used. The authors have built circuits with an input noise level equivalent to 0·3 μV for signals over the entire audiofrequency range, having a gain in excess of 50 dB.     

The integrated prism interpretation of multileg Mach-Zehnder interferometers based on multimode interference couplers

To simplify the driving conditions as well as to improve the wavelength response of multileg Mach-Zehnder interferometers (MZI) based on multimode interference (MMI) couplers we develop a new interpretation of these devices. Used for optical switching and for wavelength filtering, they are shown to work as active or passive integrated prisms. This analogy greatly facilitates the design of such components and simplifies the understanding of their functionality. The driving conditions of optical switches based on such multileg MZI are easility studied and will be reduced to basic active phase shifts. For wavelength filtering applications using such elements, a new design of the phased waveguide array is proposed which improves the characteristics of the filters.