Development of PCR-BASED DNA Markers to Identify Aand Characterise Malaysian River Catfish, Mystus Nemurus (C&V) : RAPD and AFLP

The main objectives of this study are to evaluate the usefulness of a variety of recently developed DNA markers to identify and characterise different populations of Malaysian river catfish, Mystus numerus. In the initial methodology development, 111 primers comprising of 40 single RAPD primers, 64 pairs of AFLP primers and 7 pairs of African catfish microsatellite primers were screened against M. nemurus samples. RAPD and AFLP primers gave positive results. Both techniques were also successfully used in examining the genetic diversity present in five populations of M. nemurus originating from Kedah. Perak, Johor, Sarawak and one UPM culture population. However, none of the micro satellite primers developed for the African catfish was suitable for typing our local M. nemurus. Therefore, this technique was not used for the population studies and emphasis was only given to RAPD and AFLP markers in this thesis. Nine RAPD primers and four AFLP primers detected a total of 42 and 158 polymorphic markers respectively. The modes of inheritance of the bands produced by four out of the nine RAPD primers and two out of the four AFLP primers were studied using family samples. The results showed that 9 of the RAPD markers and 24 of the AFLP markers used in population studies segregated as stable Mendelian loci while 2 RAPD markers and 13 AFLP markers showed unusual segregation. The rest of the markers could not be examined because no segregation was found in the families

Quasi-Normal Modes of a Natural AdS Wormhole in Einstein-Born-Infeld Gravity

We study the matter perturbations of a new AdS wormhole in (3+1)-dimensional Einstein-Born-Infeld gravity, called "natural wormhole", which does not require exotic matters. We discuss the stability of the perturbations by numerically computing the quasi-normal modes (QNMs) of a massive scalar field in the wormhole background. We investigate the dependence of quasi-normal frequencies on the mass of scalar field as well as other parameters of the wormhole. It is found that the perturbations are always stable for the wormhole geometry which has the general relativity (GR) limit when the scalar field mass m satisfies a certain, tachyonic mass bound m^2 > m^2_* with m^2_* < 0, analogous to the Breitenlohner-Freedman (BF) bound in the global-AdS space, m^2_BF = 3 Lambda/4. It is also found that the BF-like bound m^2_* shifts by the changes of the cosmological constant Lambda or angular-momentum number l, with a level crossing between the lowest complex and pure-imaginary modes for zero angular momentum l = 0. Furthermore, it is found that the unstable modes can also have oscillatory parts as well as non-oscillatory parts depending on whether the real and imaginary parts of frequencies are dependent on each other or not, contrary to arguments in the literature. For wormhole geometries which do not have the GR limit, the BF-like bound does not occur and the perturbations are stable for arbitrary tachyonic and non-tachyonic masses, up to a critical mass m^2_c > 0 where the perturbations are completely frozen.Comment: Added comments and references, Accepted in EPJ

BPS D-branes from an Unstable D-brane

We search for exact tachyon kink solutions of DBI type effective action describing an unstable D-brane with worldvolume gauge field turned in both the flat and a curved background. There are various kinds of solutions in the presence of electromagnetic fields in the flat space, such as periodic arrays, topological tachyon kinks, half kinks, and bounces. We identify a BPS object, D($p$-1)F1 bound state, which describes a thick brane with string flux density. The curved background of interest is the ten-dimensional lift of the Salam-Sezgin vacuum and, in the asymptotic limit, it approaches ${\rm R}^{1,4}\times {\rm T}^2\times {\rm S}^3$. The solutions in the curved background are identified as composites of lower-dimensional D-branes and fundamental strings, and, in the BPS limit, they become a D4D2F1 composite wrapped on ${\rm R}^{1,2}\times {\rm T}^2$ where ${\rm T}^2$ is inside ${\rm S}^3$.Comment: 4 pages, to appear in the proceeding of PASCOS 2005, Gyeongju, Korea, May 30-June 4, 200

Graph-Network-Based Predictive Modeling for Highly Cross-Linked Polymer Systems

In this study, a versatile methodology for initiating polymerization from monomers in highly cross-linked materials is investigated. As polymerization progresses, force-field parameters undergo continuous modification due to the formation of new chemical bonds. This dynamic process not only impacts the atoms directly involved in bonding, but also influences the neighboring atomic environment. Monitoring these complex changes in highly cross-linked structures poses a challenge. To address this issue, we introduce a graph-network-based algorithm that offers both rapid and accurate predictions. The algorithm merges polymer construction protocols with LAMMPS, a large-scale molecular dynamics simulation software. The adaptability of this code has been demonstrated by its successful application to various amorphous polymers, including porous polymer networks (PPNs), and epoxy-resins, while the algorithm has been employed for additional tasks, such as implementing pore-piercing deformations and calculating material properties

Disposable Integrated Microfluidic Biochip for Blood Typing by Plastic Microinjection Moulding

Blood typing is the most important test for both transfusion recipients and blood donors. In this paper, a low cost disposable blood typing integrated microfluidic biochip has been designed, fabricated and characterized. In the biochip, flow splitting microchannels, chaotic micromixers, reaction microchambers and detection microfilters are fully integrated. The loaded sample blood can be divided by 2 or 4 equal volumes through the flow splitting microchannel so that one can perform 2 or 4 blood agglutination tests in parallel. For the purpose of obtaining efficient reaction of agglutinogens on red blood cells (RBCs) and agglutinins in serum, we incorporated a serpentine laminating micromixer into the biochip, which combines two chaotic mixing mechanisms of splitting/recombination and chaotic advection. Relatively large area reaction microchambers were also introduced for the sake of keeping the mixture of the sample blood and serum during the reaction time before filtering. The gradually decreasing multi-step detection microfilters were designed in order to effectively filter the reacted agglutinated RBCs, which show the corresponding blood group. To achieve the cost-effectiveness of the microfluidic biochip for disposability, the biochip was realized by the microinjection moulding of COC (cyclic olefin copolymer) and thermal bonding of two injection moulded COC substrates in mass production with a total fabrication time of less than 20 min. Mould inserts of the biochip for the microinjection moulding were fabricated by SU-8 photolithography and the subsequent nickel electroplating process. Human blood groups of A, B and AB have been successfully determined with the naked eye, with 3 mu l of the whole sample bloods, by means of the fabricated biochip within 3 min.X11100104sciescopu

A serpentine laminating micromixer combining splitting/recombination and advection

Mixing enhancement has drawn great attention from designers of micromixers, since the flow in a microchannel is usually characterized by a low Reynolds number ( Re) which makes the mixing quite a difficult task to accomplish. In this paper, a novel integrated efficient micromixer named serpentine laminating micromixer (SLM) has been designed, simulated, fabricated and fully characterized. In the SLM, a high level of efficient mixing can be achieved by combining two general chaotic mixing mechanisms: splitting/recombination and chaotic advection. The splitting and recombination ( in other terms, lamination) mechanism is obtained by the successive arrangement of "F&apos;&apos;-shape mixing units in two layers. The advection is induced by the overall three-dimensional serpentine path of the microchannel. The SLM was realized by SU-8 photolithography, nickel electroplating, injection molding and thermal bonding. Mixing performance of the SLM was fully characterized numerically and experimentally. The numerical mixing simulations show that the advection acts favorably to realize the ideal vertical lamination of fluid flow. The mixing experiments based on an average mixing color intensity change of phenolphthalein show a high level of mixing performance was obtained with the SLM. Numerical and experimental results confirm that efficient mixing is successfully achieved from the SLM over the wide range of Re. Due to the simple and mass producible geometry of the efficient micromixer, SLM proposed in this study, the SLM can be easily applied to integrated microfluidic systems, such as micro-total-analysis-systems or lab-on-a-chip systems.X11159165sciescopu