Visualizing transport structures of time-dependent flow fields

This article focuses on the transport characteristics of physical properties in fluids-in particular, visualizing the finite-time transport structure of property advection. Applied to a well-chosen set of property fields, the proposed approach yields structures giving insights into the underlying flow's dynamic processes.     

Synthesis of new boron-rich building blocks for boron neutron capture therapy or energy-filtering transmission electron microscopy

The synthesis of a new ortho-carborane derivative, tetracarboranylketone 4, is reported here. Ketone 4 was prepared from a tetraalkynylated ketone by the addition of decaborane. The keto group was then easily modified to yield the glycosides 17alpha and 18beta, which contain glucose or galactose, respectively, and the nucleotide 13b. In addition to ketone 4, which is acyclic, cyclic ketone 8 was also synthesised. X-ray diffraction analysis of compound 4 indicated the presence of two toluene guest molecules per molecule of the host compound. Furthermore, compound 4 displays a rather low cytotoxicity. These novel products can be used as building blocks to create a new class of biomolecules containing high-density carborane clusters. Such molecules may constitute powerful tools for applications like Boron Neutron Capture Therapy or Energy-Filtering Transmission Electron Microscopy.     

LASER PROCESSING OF HIGH TEMPERATURE SUPERCONDUCTING THIN FILMS

High quality thin films of high temperature superconductors (HTS) have been fabricated using pulsed or cw lasers as physical vapor deposition sources. There is current interest in scaling the pulsed laser deposition (PLD) technique to coat 3-in. wafers with HTS. Process control and diagnostics relevant to achieving the required scaling and reproducibility will be reviewed.     

Throughput Analysis of a Decentralized RLAN Based on Asynchronous DS/CDMA Using Random Periodic Spreading Sequences

Packet throughput figures are obtained for a decentralized radio local area network (RLAN) which is based on asynchronous direct-sequence code-division multiple-access (DS/CDMA). Packets arrive at the receiver nodes with different power levels. Techniques are developed to derive the probability of packet success for a system employing random periodic spreading sequences. It can be shown, that this system performs far better than a network using random spreading sequences. Based on the packet error probability, throughput figures of slotted DS/CDMA-ALOHA are presented for various scenarios. The effect of applying forward error correction (FEC) is investigated. For finite user environments, additional sources of errors have to be considered. These have a major impact and reduce the overall system performance. Finally, the throughput figures of a system applying the binary exponential backoff algorithm to avoid unstable behavior is investigated. The performance figures of the various systems described in this paper show that DS/CDMA forms a valuable choice for future RLANs.     

Synthesis and crystal structure of the inter-alkali metal iodide Cs2Li3I5

Cs₂Li₃I₅ was obtained from the reaction of CsI, Li and I₂ in a sealed tantalum tube and colorless single crystals grown from the melt by slow cooling. This first inter-alkali metal iodide crystallizes in the monoclinic crystal system (C2/m, Z= 2) with a= 1666.8(6), b= 472.1(1), c= 1098.7(4) pm, β= 115.73(3)°. As the result of a x-ray crystallographic structure determination (R= 0.069, R_W= 0.066), Li⁺ is surrounded tetrahedrally (two thirds) and octahedrally (one third) by iodide. Cornersharing double chains of [LiI₄] tetrahedra are connected with edge-sharing chains of [LiI₆] octahedra to a layer of the composition [Li₃I₅]. Bicapped trigonal prisms [CsI₃] share faces and edges so that a network of the composition [Cs₂I₅] is formed which contains the necessary tetrahedral and octahedral holes for Li⁺.     

Synthesis and crystal structure of the inter-alkali-metal chloride RbLiCl2

The crystal structure of RbLiCl₂ [a= 1441.3(3), b= 412.57(8), c= 720.9(1) pm, Guinier-Simon data, orthorhombic, Ccmm, No. 63, Z= 4] was determined and refined from single crystal data, R= 0.074, R_W= 0.062. The coordination polyhedron of Rb⁺ is a bicapped trigonal prism, Li⁺ is tetrahedrally coordinated. [LiCl₄] tetrahedra are connected via common corners to undulated layers $\text{∞}\text{2}\text{[}\text{LiCl}{}^{\mathrm{c}}{}_{\mathrm{<mtext>4</mtext><mtext>2</mtext>}}\text{]}{}^{\mathrm{?}}$ parallel to (100). The structure is closely related to that of SrZnO₂.     

Uncertainty Due to Finite Resolution Measurements

We investigate the influence of finite resolution on measurement uncertainty from the perspective of the Guide to the Expression of Uncertainty in Measurement (GUM). Finite resolution in a measurement that is perturbed by Gaussian noise yields a distribution of results that strongly depends on the location of the true value relative to the resolution increment. We show that there is no simple expression relating the standard deviation of the distribution of measurement results to the associated uncertainty at a specified level of confidence. There is, however, an analytic relation between the mean value and the standard deviation of the measurement distribution. We further investigate the conflict between the GUM and ISO 14253-2 regarding the method of evaluating the standard uncertainty due to finite resolution and show that, on average, the GUM method is superior, but still approximate.