Factors affecting colour and cloud stability in a wildberry herbal drink : a thesis presented in partial fulfilment of the requirements for the degree of M. Tech. in Food Science at Massey University, Albany, New Zealand

An investigation was undertaken into the stability of the natural colour, from anthocyanins, and cloud in a Wildberry Herbal fruit drink. The fruit drinks consisted of cloudy apple and berry fruit juice with natural herb extracts and flavours. The objectives of the research were to identify the cause of cloud instability and sediment formation in the drink; determine the effect of ascorbic acid, berryfruit juice volume, storage temperature and light on anthocyanin stability; investigate the use of stabilisers to prevent sediment formation and determine consumer acceptability of a modified drink. The cause of sediment formation was determined by analysing the contribution of the major ingredients to the total amount of sediment formed. To minimise the sediment, a range of commercially available polysaccharide stabilisers were added to the drink and the amount of sediment formed determined. A consumer sensory evaluation was undertaken to determine consumer acceptability of drinks in which stabilisers had been added to improve the cloud stability. The factors affecting the anthocyanin's in the drink were analysed using a fractional factorial experimental design. The effect of the commercial pasteurisation process on the colour was also investigated. The formation of sediment was identified as being the result of complexing between the unstable cloud of the cloudy apple juice and polyphenolics, including anthocyanins, in the berryfruit juice. No sediment formed during eight weeks storage when clarified apple juice was substituted for cloudy apple juice. The sediment was reduced by approximately 45% using stabiliser systems consisting of either xanthan or a xanthan/propylene glycol alginate mixture. Consumer sensory evaluation of the modified drinks found no significant difference in liking from the standard drink. The anthocyanin loss in the drink was found to be significantly affected by increased storage temperature. Elderberry juice was found to have better colour stability over blackcurrant juice. Pasteurisation did not initially affect the colour stability of the drink. It was recommended that the composition of the Wildberry Herbal drink remain unchanged. The product should be stored at as low a temperature as possible. The drinks should be cooled to ambient temperature as quickly as possible after the pasteurisation process

The Effects of Surface Modification on Spacecraft Charging Parameters

Charging of materials by incident radiation is affected by both environmental and physical conditions. Modifying a material’s physical surface will change its reflection, transmission and absorption of the incident radiation which are integrally related to the accumulation of charge and energy deposition in the material. An optical analysis of the effect of surface modification on spacecraft charging parameters on prototypical Kapton HN and Cu samples is presented. Samples were roughened with abrasive compounds ranging from 0.5 to 10 μm in size, comparable to the range of incident wavelengths. They were also contaminated with thin layers of DC 704 diffusion pump oil. Using a UV/VIS/NIR light source and a diffraction grating spectrometer, measurements were performed on pristine and modified materials. The measured spectra confirmed that surface modification does induce changes in optical reflection, transmission, and absorption. The generally increased absorption observed results in increased photon energy deposited in the material, leading to increased charge emission through the photoelectric effect. Index Terms—About reflectivity, surface modification, spacecraft charging, photoyiel

Critical Casimir Forces and Colloidal Phase Transitions in a Near-Critical Solvent : A Simple Model Reveals a Rich Phase Diagram

From experimental studies it is well-known that colloidal particles suspended in a near-critical binary solvent exhibit interesting aggregation phenomena, often associated with colloidal phase transitions, and assumed to be driven by long-ranged solvent mediated (SM) interactions (critical Casimir forces), set by the (diverging) correlation length of the solvent. We present the first simulation and theoretical study of an explicit model of a ternary mixture that mimics this situation. Both the effective SM pair interactions and the full ternary phase diagram are determined for Brownian discs suspended in an explicit two-dimensional supercritical binary liquid mixture. Gas-liquid and fluid-solid transitions are observed in a region that extends well-away from criticality of the solvent reservoir. We discuss to what extent an effective pair-potential description can account for the phase behavior we observe. Our study provides a fresh perspective on how critical fluctuations of the solvent might influence colloidal self-assembly.Comment: 4 pages, 4 figure

Using utilization profiles in allocation and partitioning for multiprocessor systems

Journal ArticleThe problems of multiprocessor partitioning and program allocation are interdependent and critical to the performance of multiprocessor systems. Minimizing resource partitions for parallel programs on partitionable multiprocessors facilitates greater processor utilization and throughput. The processing resource requirements of parallel programs vary during program, execution and are allocation dependent. Optimal resource utilization requires that resource requirements be modeled as variable over time. This paper investigates the use of program profiles in allocating programs and partitioning multiprocessor systems. An allocation method is discussed. The goals of this method are to (1) minimize program execution time, (2) minimize t h e total number of processors used, (3) characterize variation in processor requirements over the lifetime of a program, (4) to accurately predict the impact on run time of the number of processors available at any point in time and (5) to minimize fluctuations in processor requirements to facilitate efficient sharing of processors between partitions on a partitionable multiprocessor. An application to program partitioning is discussed that improves partition run times compared to other methods

DPOS: A metalanguage and programming environment for parallel processors

Journal ArticleThe complexity and diversity of parallel programming languages and computer architectures hinders programmers in developing programs and greatly limits program portability. All MIMD parallel programming systems, however, address common requirements for process creation, process management, and interprocess communication. This paper describes and illustrates a structured programming system (DPOS) and graphical programming environment for generating and debugging high-level MIND parallel programs. DPOS is a metalanguage for defining parallel program networks based on the common requirements of distributed parallel computing that is portable across languages, modular, and highly flexible. The system uses the concept of stratification to separate process network creation and the control of parallelism form computational work. Individual processes are defined within the process object layer as traditional single threaded programs without parallel language constructs. Process networks and communication are defined graphically within the system layer at a high level of abstraction as recursive graphs. Communication is facilitated in DPOS by extending message passing semantics in several ways to implement highly flexible message passing constructs. DPOS processes exchange messages through bi-directional channel objects using guarded, buffered, synchronous and asynchronous communication semantics. The DPOS environment also generates source code and provides a simulation system for graphical debugging and animation of the programs in graph form

Orbital-Free Density Functional Theory: Kinetic Potentials and Ab-Initio Local Pseudopotentials

In the density functional (DF) theory of Kohn and Sham, the kinetic energy of the ground state of a system of noninteracting electrons in a general external field is calculated using a set of orbitals. Orbital free methods attempt to calculate this directly from the electron density by approximating the universal but unknown kinetic energy density functional. However simple local approximations are inaccurate and it has proved very difficult to devise generally accurate nonlocal approximations. We focus instead on the kinetic potential, the functional derivative of the kinetic energy DF, which appears in the Euler equation for the electron density. We argue that the kinetic potential is more local and more amenable to simple physically motivated approximations in many relevant cases, and describe two pathways by which the value of the kinetic energy can be efficiently calculated. We propose two nonlocal orbital free kinetic potentials that reduce to known exact forms for both slowly varying and rapidly varying perturbations and also reproduce exact results for the linear response of the density of the homogeneous system to small perturbations. A simple and systematic approach for generating accurate and weak ab-initio local pseudopotentials which produce a smooth slowly varying valence component of the electron density is proposed for use in orbital free DF calculations of molecules and solids. The use of these local pseudopotentials further minimizes the possible errors from the kinetic potentials. Our theory yields results for the total energies and ionization energies of atoms, and for the shell structure in the atomic radial density profiles that are in very good agreement with calculations using the full Kohn-Sham theory.Comment: To be published in Phys. Rev.