Estimation of the emission temperature of an electrodeless discharge lamp and determination of the oscillator strength for the I(P3/2) 183.038 nm resonance transition

The 183.038 nm resonance absorption transition of I(²P_3/2) has been studied using a flash photolysis set-up for gas-phase chemistry and a radio frequency powered electrodeless discharge lamp filled with iodine. The dependence of self-absorption and self-reversal on iodine partial pressure in the discharge volume was measured. The optimum iodine partial pressure, with self-absorption minimized and acceptable intensity, is determined to be approximately 2.5×10⁻³ mbar. A method is described to estimate the temperature of the emitting atoms using direct measurements of relative absorption at different absorber concentrations. This yields an emission temperature of 923±50 K. Using this temperature, the oscillator strength for the I(²P_3/2) transition at 183.038 nm is determined to be f=(3.87±0.57)×10⁻³, corresponding to an absorption cross-section at the center of the line of σ=(5.42±0.8)×10⁻¹⁴ cm² atom⁻¹_. This shows a difference from one of two earlier measurements, but is close to the other. The remaining difference from the latter measurement is probably due to tendencies of opposite biases inherent to the experiments.     

The electron affinity of tellurium

The electron affinity of tellurium has been determined to 1.970 876(7) eV. The threshold for photodetachment of Te^-(² P _3/2) forming neutral Te in the ground state was investigated by measuring the total photodetachment cross section using a collinear laser-ion beam geometry. The electron affinity was obtained from a fit to the Wigner law in the threshold region.     

Functionalization of substituted 2(1H)- and 4(1H)-pyridones. III. The preparation of substituted 6-Vinyl-1,2-dihydro-2-oxo- and 1,4-dihydro-4-oxo-3-pyridinecarboxylic acids through the chemistry of pyridone dianions

The synthesis of various substituted 6-vinyl-1,2-dihydro-2-oxo-3-pyridinecarboxylic acids from the dianions of 1,2-dihydro-6-methyl-2-oxo-3-pyridinecarbonitrile and the corresponding 3-t-butyl ester is reported. The dianions were generated with LDA in THF at low temperature and reacted with various carbonyl substrates. Several conditions for the dehydration and hydrolysis of these adducts to the vinyl pyridone acids are discussed. Employing the conditions used for the 2-pyridone analogs, a series of substituted 6-vinyl-1,4-di-hydro-4-oxo-3-pyridinecarboxylic acids was prepared through the new dianion of 1,4-dihydro-6-methyl-4-oxo-3-pyridinecarboxylic acid, t-butyl ester.     

Constrained control of a nonlinear two point boundary value problem,I

In this paper we consider an optimal control problem for a nonlinear second order ordinary differential equation with integral constraints. A necessary optimality condition in form of the Pontryagin minimum principle is derived. The proof is based on McShane-variations of the optimal control, a thorough study of their behaviour in dependence of some denning parameters, a generalized Green formula for second order ordinary differential equations with measurable coefficients and certain tools of convex analysis.Dedicated to Lothar von Wolfersdorf on the occasion of his 60th birthday     

On the Local Representation of G-Closure

We give a representation for the G-closure of the set of elliptic operators defined by means of the Nemitskii operators , , where the functions a _i are strongly monotone and belong to given sets of uniformly Lipschitz functions, but where the characteristic functions satisfy standard volume restrictions.     

Flow-driven orientation dynamics of semiflexible fiber systems

We study the flow-induced orientation dynamics of semiflexible fibers in dilute fiber suspensions. Starting from the equations of motion for a two-rod model of flexible fibers in Stokes flow, the Smoluchowski equation for a connected monomer orientation distribution function is derived. We then obtain a set of equations for the time dependence of the first and second moments of the orientation distribution function, thus extending the Folgar Tucker equations for short rigid fiber suspensions to flexible fiber suspensions. The resulting generalized equations for the orientation dynamics of a suspension of flexible fibers are solved for simple channel flow. It is shown that all qualitative effects of bending and straightening of fibers and their influence on the orientation of flexible fibers are captured within our model. A scalar measure for the distribution of bending in a flow is introduced, which allows to detect the degree of bending of fibers. Paper was presented at the 3rd Annual Rheology Conference, AERC 2006, April 27–29, 2006, Crete, Greece.     

Comparative numerical study of two concentrated fiber suspension models

We consider two rheological models for concentrated fiber suspensions. In both models the equations for orientation and flow are fully coupled, i.e., the orientation influences the flow via a constitutive relation for the viscosity and the orientation of the fibers is determined by the flow field. The orientation state of the fibers is characterized by the Advani–Tucker orientation tensor. We are investigating suspensions of fibers in which the kinetic energies of the fibers are large compared to the thermal energies, i.e., the influence of Brownian motion may be neglected. The first model is the Folgar–Tucker model with backcoupling to the flow (FT model). The second model is an extension of Folgar–Tucker, which models phenomenologically the topological exclusion interaction in dense suspensions (FTMS model). As test cases for the simulation are considered channel flow, 8:1 contraction flow and flow around a cylinder.     

Dihydrocytosines and cytokines from 3-aminopropionitriles

The synthesis of dihydrocytosines 4 from 3-aminopropionitriles 1 has been broadened and the dihydrocytosines themselves have now been successfully converted to cytosines 9 . Unsubstituted 3-(H, alkyl or aryl) aminopropionitriles ( 1 , X = H) convert with cyanate to 1-(H, alkyl or aryl)-1-(2-cyanoethyl)ureas ( 2 , X = H), which in turn easily cyclize with anhydrous strong acid or base to 1-(H, alkyl or aryl)-5,6-dihydrocytosines ( 4 , X = H). The 1-arylaminopropionitriles ( 1 , X = H) which are poorly reactive with cyanic acid combine readily with benzoylureas to form 3-benzoyl-1-(2-cyanoethyl)-1-arylureas ( 3 , X = H). These benzoylureas likewise cyclize with strong acid or base but with simultaneous elimination of the benzoyl moiety to yield the 1-aryldihydrocytosines 4 (X = H). Amines have successfully been added to 2-chloroacrylonitrile to yield 2-chloro-3-(amino and substituted amino)propionitriles ( 1 , X = Cl). These 2-chloropropionitriles also could be converted with cyanate or benzoylisocyanate to ureas and benzoylureas, respectively (1-(H or alkyl)-1-(2-chloro-2-cyanoethyl)ureas ( 2 , X = Cl) or 1-(H or alkyl)-1-(2-chloro-2-cyanoethyl)-3-benzoylureas ( 3 , X = Cl). The chlorine substituted ureas were unstable especially to base and to heat but with anhydrous acid were cyclized in high yield to 1-(H or alkyl)-5-chloro-5,6-dihydro-cytosines ( 4 , X = Cl). Direct chlorination of unsubstituted dihydrocytosines 4 (X = H) did not afford these same 5-chlorodihydrocytosines 4 (X = Cl) under any conditions investigated. 1-Ethyl-5,6-dihydrocytosine ( 4b ) as the cation (hydrobromide) is converted directly in good yield to 1-ethylcytosine hydrobromide ( 7 ) by bromine in nitrobenzene at 140-160° in a concomitant bromination dehydrobromination reaction. 1-(Alkyl or aryl)-5,6-dihydrocytosines ( 4 , X = H) are halogenated at low temperature in the presence of base to form (N³ or N⁴)halogenodihydrocytosines ( 8 , R = H). The N-chlorodihydrocytosines 8 are stable. The N-bromo and N-iodo compounds isomerize spontaneously to 5-halogeno-5,6-dihydrocytosines ( 4 , X = Br, I; R = H). The 5-halogeno-5,6-dihydrocytosines 4 (X = Cl, Br, I) whether from cyclization or direct halogenation are readily dehydrohalogenated to the corresponding cytosines 9.     

Application of sorbent obtained by pyrolysis of sewage sludge for biological treatment of waste water

Applied Biochemistry and Biotechnology - The investigation of the behavior of the waste-water sludge of various chemical enterprises during thermal processing shows that effective carbon-mineral...