The turbulent wake of a circular cylinder rotating about the streamwise axis

This paper presents measurements in the turbulent wake of a circular cylinder rotating with its axis normal to the free-stream velocity; in other words, the axis of rotation was parallel to the streamwise direction. All three mean velocities and six Reynolds stresses were obtained at three positions downstream of the cylinder, with and without rotation of the free-stream. Most emphasis is given to the latter results because of the better flow quality. The ratio of the circumferential velocity of the cylinder to the free-stream velocity — the swirl number — had a maximum value of 0.6. Measurements for two combinations of the free-stream and angular velocities showed the velocity deficit in the wake to be a multi-valued function of the swirl number, implying that the rotation affected the separation of the cylinder's boundary layer in a complex manner. In the turbulent wake, the rotation did not significantly alter the magnitudes of the normal stresses, but caused large changes to the shape of the profiles of the axial and cross-stream normal stresses. Eventually, the primary (cross-stream) shear stress became almost entirely positive, but there was no corresponding change to the (cross-stream) gradient of the streamwise mean velocity. Despite these alterations to the turbulence, the rotationally-activated generation terms in the Reynolds transport equations never dominated the terms that are common to the wakes of rotating and non-rotating cylinders.This work was supported by the Australian Research Council. Most of the data acquisition software was written by Mr J. J. Smith.     

Improving the Switching Capacity of Glyco-Self-Assembled Monolayers on Au(111)

Self-assembled monolayers (SAMs) decorated with photoisomerizable azobenzene glycosides are useful tools for investigating the effect of ligand orientation on carbohydrate recognition. However, photoswitching of SAMs between two specific states is characterized by a limited capacity. The goal of this study is the improvement of photoswitchable azobenzene glyco-SAMs. Different concepts, in particular self-dilution and rigid biaryl backbones, have been investigated. The required SH-functionalized azobenzene glycoconjugates were synthesized through a modular approach, and the respective glyco-SAMs were fabricated on Au(111). Their photoswitching properties have been extensively investigated by applying a powerful set of methods (IRRAS, XPS, and NEXAFS). Indeed, the combination of tailor-made biaryl-azobenzene glycosides and suitable diluent molecules led to photoswitchable glyco-SAMs with a significantly enhanced and unprecedented switching capacity.     

Extraction of Co-Products from Biomass: Example of Thermal Degradation of Silymarin Compounds in Subcritical Water

In an effort to increase revenues from a given feedstock, valuable co-products could be extracted prior to biochemical or thermochemical conversion with subcritical water. Although subcritical water shows significant promise in replacing organic solvents as an extraction solvent, compound degradation has been observed at elevated extraction temperatures. First order thermal degradation kinetics from a model system, silymarin extracted from Silybum marianum, in water at pH 5.1 and 100, 120, 140, and 160 °C were investigated. Water pressure was maintained slightly above its vapor pressure. Silymarin is a mixture of taxifolin, silichristin, silidianin, silibinin, and isosilibinin. The degradation rate constants ranged from 0.0104 min⁻¹ at 100 °C for silichristin to a maximum of 0.0840 min⁻¹ at 160 °C for silybin B. Half-lives, calculated from the rate constants, ranged from a low of 6.2 min at 160 °C to a high of 58.3 min at 100 °C, both for silichristin. The respective activation energies for the compounds ranged from 37.2 kJ/gmole for silidianin to 45.2 kJ/gmole for silichristin. In extracting the silymarin with pure ethanol at 140 °C, no degradation was observed. However, when extracting with ethanol/water mixtures at and 140 °C, degradation increased exponentially as the concentration of water increased. An erratum to this article can be found at     

Topology optimization of 3D shell structures with porous infill

This paper presents a 3D topology optimization approach for designing shell structures with a porous or void interior. It is shown that the resulting structures are significantly more robust towards load perturbations than completely solid structures optimized under the same condi-tions. The study indicates that the potential benefit of using porous structures is higher for lower total volume fractions. Compared to earlier work dealing with 2D topology opti-mization, we found several new effects in 3D problems. Most notably, the opportunity for designing closed shells signifi-cantly improves the performance of porous structures due to the sandwich effect. Furthermore, the paper introduces improved filter boundary conditions to ensure a completely uniform coating thickness at the design domain boundary.     

The off-line group seat reservation problem

In this paper we address the problem of assigning seats in a train for a group of people traveling together. We consider two variants of the problem. One is a special case of two-dimensional knapsack where we consider the train as having fixed size and the objective is to maximize the utilization of the seats in the train. The second is a special case of two-dimensional bin packing where all requests must be accommodated while trying to minimize the number of passenger cars needed. For both variants of the problem we present a number of bounds and develop exact algorithms. Computational results are presented for various instances based on realistic data, and from the packing literature adapted to the problems addressed.     

Lysine production in continuous culture

Applied Biochemistry and Biotechnology - Lysine is an essential amino acid that is widely used as a feed additive. Many animal feeds are deficient in lysine, so the lysine, as well as other amino...     

Effect of particle size on carburization of Fe-Co alloy catalysts

Bimetallic Fe-Co alloy catalysts supported on silica have been studied by use of combined Mössbauer absorption and emisson spectroscopy. Effects of carburization on samples with different particle size are discussed.     

Chemoenzymatic synthesis of sialylated glycopeptides derived from mucins and T-cell stimulating peptides.

The Tn, T, sialyl-Tn, and 2,3-sialyl-T antigens are tumor-associated carbohydrate antigens expressed on mucins in epithelial cancers, such as those affecting the breast, ovary, stomach, and colon. Glycopeptides carrying these antigens are of interest for development of cancer vaccines and a short, chemoenzymatic strategy for their synthesis is reported. Building blocks corresponding to the Tn (GalNAc alpha-Ser/Thr) and T [Gal beta(1-->3)GalNAc alpha-Ser/Thr] antigens, which are relatively easy to obtain by chemical synthesis, were prepared and then used in the synthesis of glycopeptides on the solid phase. Introduction of sialic acid to give the sialyl-Tn [Neu5Ac alpha(2-->6)GalNAc alpha-Ser/Thr] and 2,3-sialyl-T [Neu5Ac alpha(2-->3)Gal beta(1-->3)GalNAc alpha-Ser/Thr] antigens is difficult when performed chemically at the building block level. Sialylation was therefore carried out with recombinant sialyltransferases in solution after cleavage of the Tn and T glycopeptides from the solid phase. In the same manner, the core 2 trisaccharide [Gal beta 1-->3(GlcNAc beta 1-->6)GalNAc] was incorporated in glycopeptides containing the T antigen by using a recombinant N-acetylglucosaminyltransferase. The outlined chemoenzymatic approach was applied to glycopeptides from the tandem repeat domain of the mucin MUC1, as well as to neoglycosylated derivatives of a T cell stimulating viral peptide.     

Solving Large Quadratic Assignment Problems in Parallel

Quadratic Assignment problems are in practice among the mostdifficult to solve in the class of NP-complete problems. Theonly successful approach hitherto has been Branch-and-Bound-basedalgorithms, but such algorithms are crucially dependent on good boundfunctions to limit the size of the space searched. Much work hasbeen done to identify such functions for the QAP, but with limitedsuccess.Parallel processing has also been used in order to increase the sizeof problems solvable to optimality. The systems used have, however, oftenbeen systems with relatively few, but very powerful vector processors, andhave hence not been ideally suited for computations essentially involving non-vectorizable computations on integers.In this paper we investigate the combination of one of the best bound functions for a Branch-and-Bound algorithm (the Gilmore-Lawler bound) and various testing, variable binding and recalculation of bounds between branchings when used in aparallel Branch-and-Bound algorithm. The algorithm has been implemented on a 16-processor MEIKO Computing Surface with Intel i860processors. Computational results from the solution of a number of large QAPs, including the classical Nugent 20 are reported.