Brownian beads

We show that the past and future of half-plane Brownian motion at certain cutpoints are independent of each other after a conformal transformation. Like in Ito's excursion theory, the pieces between cutpoints form a Poisson process with respect to a local time. The size of the path as a function of this local time is a stable subordinator whose index is given by the exponent of the probability that a stretch of the path has no cutpoint. The index is computed and equals 1/2.Comment: 24 pages, 1 figur

Trilobitenperlen from Dunaszekcső (Hungary)

In the Csanády-collection (Bátaszék, Hungary) there are two unpublished two-channelled glass beads. They had been found on the banks of the river Danube in Dunaszekcsô in Hungary by a fisherman and were presented to the Csanády-collection in or after 1965 (Mrs Csanády pers. comm.). These special beads are called Rippen-glasperlen (Noll 1963, 68) or Trilobitenperlen (Haevernick 1974, 105) in the literature. One can set up two main groups of Trilobitenperlen on the basis of decoration: 1. beads with figurative decoration, which are also called two-channelled glass cameos (Gesztelyi 1997) and 2. beads without figurative decoration. T. E. Haevernick, who set up a basic typology for the Trilobitenperlen further divided the non-figurative beads into Glatt-gerript type and Kariert-gerript type (Havevernick 1974, 106)

Brownian Dynamics Studies on DNA Gel Electrophoresis. II. `Defect' Dynamics in the Elongation-Contraction Motion

By means of the Brownian dynamics (BD) method of simulations we have developed, we study dynamics of individual DNA undergoing constant field gel electrophoresis (CFGE), focusing on the relevance of the `defect' concept due to de Gennes in CFGE. The corresponding embodiment, which we call {\it slack beads} (s-beads) is explicitly introduced in our BD model. In equilibrium under a vanishing field the distance between s-beads and their hopping range are found to be randomly distributed following a Poisson distribution. In the strong field range, where a chain undergoes the elongation-contraction motion, s-beads are observed to be alternatively annihilated in elongation and created in contraction of the chain. On the other hand, the distribution of hopping range of s-beads does not differ much from that in equilibrium. The results indicate that the motion of the chain elongated consists of a huge number of random movements of s-beads. We have also confirmed that these features of s-beads agree qualitatively with those of s-monomers in the extended bond fluctuation model (EBFM) which we recently proposed. The coincidence of the two simulations strongly supports the stochastic semi-local movement of s-monomers which we {\it a priori} introduced into the EBFM.Comment: 14 pages, 11 figure

Reductive Biotransformation of Ethyl Acetoacetate: A Comparative Studies using Free and Immobilized Whole Yeast Cells

Bioreduction of ethyl acetoacetate with free and immobilized yeast whole cell was achieved by using water and sucrose combination. After detachment from immobilized beads under basic condition, the corresponding ethyl(S)-(+)-3-hydroxybutanoate was isolated with 98 to 100% yield. Immobilized beads of yeast whole cell were prepared at different temperature which affects the morphology and physiology of the beads for the diffusion of the enzyme, which shown the maximum conversion of the substrate to products as compared to the free yeast whole cell

Novel particulate vaccine candidates recombinantly produced by pathogenic and nonpathogenic bacterial hosts : a thesis presented in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Microbiology at Massey University, Manawatu, New Zealand.

Polyhydroxyalkanoates (PHAs) are biopolyesters synthesized as small spherical cytoplasmic inclusion bodies by a range of bacteria. Recently, PHA beads have been investigated for use as a vaccine delivery platform by using engineered heterologous production hosts that allowed the efficient display of vaccine candidate antigens on the beads surface and were found to greatly improve immunogenicity of the displayed antigens. However, like other subunit vaccines, these antigen-displaying (vaccine) PHA beads only provide a limited repertoire of antigens. In this thesis we investigate the idea of directly utilizing the disease causative pathogen or model organism to produce vaccine PHA beads with a large antigenic repertoire. These beads are hypothesized to have the potential to induce greater protective immunity compared to production of the same PHA bead in a heterologous production host. This concept was exemplified with Pseudomonas aeruginosa and Mycobacterium tuberculosis as model human pathogens. For P. aeruginosa we describe the engineering of this bacterium to promote PHA and Psl (polysaccharide) production. This represents a new mode of functional display for the engineering, production, and validation of a novel OprI/F-AlgE fusion antigen-displayed on PHA beads. For the disease tuberculosis we investigated the use of nonpathogenic M. smegmatis as a model organism for M. tuberculosis. We described the bioengineering, production, and validation of Ag85AESAT- 6 displayed on PHA beads produced in M. smegmatis. Here we showed that both organisms were harnessed to produce custom-made PHA beads for use as particulate subunit vaccines that carried copurifying pathogen-derived proteins as a large antigenic repertoire and the ability of these vaccine PHA beads to generate a protective immune response. This novel bioengineering concept of particulate subunit vaccine production could be applied to a range of pathogens naturally producing PHA inclusions for developing efficacious subunit vaccines for infectious diseases

Formulation and evaluation of floating mucoadhesive alginate beads for targetingHelicobacter pylori

Objectives: There are various obstacles in the eradication of Helicobacter.pylori (H. pylori) infections, including low antibiotic levels and poor accessibility of the drug at the site of the infection. This study describes the preparation and characterisation of novel floating-mucoadhesive alginate beads loaded with clarithromycin (CMN) for delivery to the gastric mucosa to improve the eradication of this micro-organism. Methods: Calcium alginate beads were prepared by ionotropic gelation. The formulation was modified through addition of oil and coating with chitosan in order to improve floating, mucoadhesion and modify drug release. Key findings: SEM confirmed the sphericity of the beads with X-ray microtomography (XμMT) showing the 3D structure of the beads with the layered internal structure of the bead and the even distribution of the drug within the bead. This formulation combined two gastro-retentive strategies and these formulations produced excellent in vitro floating, mucoadhesive and drug release characteristics. Enhanced stability of the beads in phosphate buffer raises a potential for the modified formulations to be targeted to regions of higher pH within the gastrointestinal tract with a higher pH. Drug release from these beads was sustained through an unstirred mucin layer simulating in vivo conditions under which the H. pylori resides in the gastric mucosa. Conclusions: This novel formulation will ensure retention for a longer period in the stomach than conventional formulations and control drug release, ensuring high local drug concentrations, leading to improved eradication of the bacteria

Refractometry of organosilica microspheres

The refractive index of novel organosilica (nano/micro)material is determined using two methods. The first method is based on analysis of optical extinction efficiency of organosilica beads versus wavelength, which is obtained by a standard laboratory spectrometer. The second method relies on the measurable trapping potential of these beads in the focused light beam (laser tweezers). Polystyrene beads were used to test these methods, and the determined dispersion curves of refractive index values have been found accurate. The refractive index of organosilica beads has been determined to range from 1.60-1.51 over the wavelength range of 300-1100 nm.Comment: 9 pages, 8 figure