Inversion with regularization for the retrieval of tropospheric aerosol parameters from multiwavelength lidar sounding

We present an inversion algorithm for the retrieval of particle size distribution parameters, i.e., mean (effective) radius, number, surface area, and volume concentration, and complex refractive index from multiwavelength lidar data. In contrast to the classical Tikhonov method, which accepts only that solution for which the discrepancy reaches its global minimum, in our algorithm we perform the averaging of solutions in the vicinity of this minimum. This averaging stabilizes the underlying ill-posed inverse problem, particularly with respect to the retrieval of number concentration. Results show that, for typical tropospheric particles and 10% error in the optical data, the mean radius could be retrieved to better than 20% from a lidar on the basis of a Nd:YAG laser, which provides a combination of backscatter coefficients at 355, 532, and 1064 nm and extinction coefficients at 355 and 532 nm. The accuracy is improved if the lidar is also equipped with a hydrogen Raman shifter. In this case two additional backscatter coefficients at 416 and 683 nm are available. The combination of two extinction coefficients and five backscatter coefficients then allows one to retrieve not only averaged aerosol parameters but also the size distribution function. There was acceptable agreement between physical particle properties obtained from the evaluation of multiwavelength lidar data taken during the Lindenberg Aerosol Characterization Experiment in 1998 (LACE 98) and in situ data, which were taken aboard aircraft.     

Ermittlung der Sequenzverteilung und Taktizität bei Acrylnitrill/Vinylidenchlorid-Copolymeren

An acrylonitrile/vinylidene chloride copolymer prepared by continuous suspension polymerization in aqueous medium was examined by carbon magnetic resonance at 90.52 MHz. The sequence distribution was evaluated from the diad and tetrad distribution of the methylene carbon regions and from the triad distributions of the other carbon atoms. The stereochemical configuration of the acrylonitrile units was determined from the peaks of the methine and the nitrile carbons which showed a low preference of the isotactic triad against the syndiotactic triad in agreement with freeradical polymerized polyacrylonitrile.     

Production and physicochemical characterization of resistant starch type III derived from pea starch

Smooth pea starch was used for the production of physiological important resistant starch type III. For reduction of the molecular weight of the starch, different strategies including enzymatic debranching and acid hydrolysis (lintnerization), were tested to obtain an optimal starting material for retrogradation. The resulting polymer chain lengths were analyzed by high-performance anion-exchange chromatography. Temperature regimes and starch concentrations in gel were optimized during the retrogradation with the aim to obtain a high yield of resistant starch. Optimal conditions led to resistant starch contents up to 74%. The products were thermostable and showed no loss of resistant structures after autoclaving. The peak temperatures of the thermal transition were at approximately 147 degrees C. The resulting resistant starch products are suitable for the generation of functional foods.     

Dimensioning of membrane bioreactors for municipal wastewater treatment.

A basic procedure is proposed for dimensioning membrane bioreactors that is generally applicable. It evaluates the required membrane surface with particular consideration of loading combinations and hydraulic loading characteristics; it also takes into account ranges of minimum temperatures and corresponding fluxes as given by suppliers. The procedures, while likely to require further improvement, should make MBR design more transparent and aid the comparison of design variants.     

Preparation of defined bulk densities for using the capillary rise method in the case of fine powders

The wetting properties of powders are important in many technological processes. Contact angles can be characterized by an effective contact angle of the particle arrangement relative to the wetting liquid, but their quantification is problematic. An exact determination depends on an accurate preparation of the test samples. A defined pre-consolidation by vertical shocks is introduced in this paper.     

Trees,grids, and MSO decidability: From graphs to matroids

Monadic second order (MSO) logic has proved to be a useful tool in many areas of application, reaching from decidability and complexity to picture processing, correctness of programs and parallel processes. To characterize the structural borderline between decidability and undecidability is a classical research problem here. This problem is related to questions in computational complexity, especially to the model checking problem, for which many tools developed in the area of decidability have proved to be useful. For more than two decades it was conjectured in [D. Seese, The structure of the models of decidable monadic theories of graphs, Ann. Pure Appl. Logic 53 (1991) 169–195] that decidability of monadic theories of countable structures implies that the theory can be reduced via interpretability to a theory of trees.     

Rapid differentiation of new apple cultivars by headspace solid‐phase microextraction in combination with chemometrical data processing

The aim of this study was to test a combination of automated headspace solid phase‐microextraction gas chromatography (GC) with chemometrical data treatment for the rapid differentiation of enzyme‐inactivated homogenates of new apple cultivars. The four cultivars Pinova, Piflora, Renora and Florina are characterized by different volatile patterns. Differences in the contents of volatiles were especially found for butyl acetate, ethyl butanoate, 2‐methyl butanol, ethyl acetate and 6‐methyl‐5‐hepten‐2‐ol. The used sample preparation method for GC coupled with pattern recognition of chromatograms is a useful tool for rapid and reliable determination of large numbers of samples.