No description available.

Distribution, cytological organization and development of laticifers In some latex bearing plants were studied by the use of optical and electron microscopy. Seven species from five different families were used In a comparative study, which were Meconopsis cambrica & Papaver rhoeas (Papaveraceae), Hevea brasiliensis & Euphorbia wulfenii (Euphorbiaceae), Musa acuminata (Musaceae), Mandevilla splendens (Apocyanaceae) & Taraxacum officinale (Compositae/Asteraceae). Several preparation procedures have been compared and optimised for the structural preservation of the laticifers and for examination of their distribution in these taxa. Methods of fixation have been studied. Fresh unfixed samples showed good structural information and laticifer distribution in the tissue. This technique was also very fast and convenient to use. In practice this protocol can be applied in monitoring and screening bulk samples in a breeding program, where speed and convenience are very important. Samples fixed with aldehyde fixative gave reasonably good results for histology study but not at the electron microscope level. The samples fixed with this fixative however, were highly suited to Immunohistochemical work. This information is invaluable and will be used and adapted for Hevea study in Malaysia. Both osmium and a combination of osmium tetroxide and zinc iodide were superior in term of ultrastructural preservation. Embedding media for laticifers were compared. For histological and immunohistochemical studies, Paraplast wax was used. The preparation procedure was easy and convenient, and overall structural information of laticifers was good. Spurr resin and araldite are both epoxy resins, but samples embedded in araldite gave better, more acceptable results. The carcinogenic nature of Spun- resin means that it must be handled with extreme caution, making it a less convenient embedding medium. The only acrylic resin was LR White, which was initially Intended for an immunocytochemistry study where the priority was to retain antigenic sites. Samples embedded with this resin did not show good structural information. The final set of procedures evaluated was staining methods. The staining procedure has to be fast, must differentially stain laticifers and must be reliable. These stains can be grouped into two categories; standard histological stains such as Toluidine Blue and Safranin O with Astra Blue, and fluorescent stains such as Calcofluor, ANS and Acridine Orange. However almost all stains tested failed to differentially stain latex or laticifers. They however did assist in clarifying for identification the location and distribution of laticifers in the tissues. Using Toluidine Blue was very fast and easy, but all the fluorescent stains are faster and easier to use. Laticifers in all species examined, exhibited a similar pattern of distribution. They were located in the cambial regions of stems, petioles, leaves and roots, or closely located within the vascular bundle.

No description available.

This research aims to add to the current knowledge available for miniemulsion polymerization reactions and to use this knowledge to synthesize multifunctional nanosized latex particles that have the potential to be used in catalysis. The physical properties of the latex can be adjusted to suit various environments due to the multiple functional groups present. For this research, styrene, pentafluorostyrene, azidomethyl styrene, pentafluorostyrene with azidomethyl styrene and pentafluorostyrene with styrene latexes were produced, and analyzed by dynamic light scattering. The latexes were synthesized using a miniemulsion polymerization technique found through this research. Potassium oleate and potassium 1,1,2,2,3,3,4,4-nonafluorobutane-1-sulfonate were used as surfactants during the miniemulsion polymerization reaction to synthesize pentafluorostyrene with azidomethyl styrene latex. Transmission electron microscopy data and dynamic light scattering data have been collected to analyze the structure of this latex, and it has been synthesized using a number of conditions, differing in reaction time, surfactant amount and sonication methods. We have also improved the solubility of the latex through a copper(I) catalyzed 1,3-dipolar azide-alkyne reaction, by clicking (polyethylene glycol)5000 onto the azide functional groups.

Fines have a very important role in paper chemistry and are a determinant in retention, drainage and the properties of paper. The purpose of this project was to be able to label the fines with fluorophores and study their Brownian motion with fluorescence microscopy. When succeeded this could then be used to study fines, fibers and other additives in a suspension thus giving the fundamental knowledge of why fines have this important role. Due to aggregation of the fines no Brownian motion could be detected. Instead the fines were handled as a network system and small fluorescence labeled latex particles were then studied in this system. This approach yields information about the fines when the obstacle with sedimentation of the network is resolved. / Fines har en viktig roll i papperskemin och har en avgörande roll när det gäller retention, dränering och papprets egenskaper. Syftet med detta projekt var att kunna färga in fines med fluoroforer och sedan följa deras brownska rörelse med hjälp av ett fluorescensmikroskop. Denna metod skulle sedan kunna användas för att observera interaktionerna mellan fines, fibrer och andra additiver i en suspension. Det skulle göra de underliggande mekanismerna kända för varför fines utgör en så viktig del i processen. På grund av att fines aggregerade så fick man istället behandla dem som ett nätverk där man tillsatte redan fluorescerande prober vars rörelser studerades. Att studera fines indirekt på detta vis kommer att ge information när sedimenteringen av nätverket är löst.

L'objectif de ce travail est de surmonter tous ces processus long et fastidieux comme la filtration et la centrifugation qui sont utilisées dans l'application in-vitro. En plus, ces particules qui sont appropriés pour une utilisation dans le laboratoire-sur une-puce et les biocapteurs systèmes sont produites. Les particules submicroniques magnétiques de latex (MLPs) avec la morphologie noyaucoque souhaité ont été préparées. L'huile dans eau (h/e) et l'émulsion magnétique (faitmaison) a été utilisé en tant que graine de polymérisation radicalaire en émulsion de styrène (St) en tant que monomère et agent de reticulation divenylbenzene (DVB) en présence de persulfate de potassium qu'initiateur. Les particules de la surface ont été fonctionnalisés avec du sulfate et des groupes carboxyliques en utilisant les initiateurs. Un nouveau biocapteur électrochimique de capacité basé sur de substrat de nitrure de silicium (Si3N4) combiné à des MLPs a été développé. MLPs avec terminaison acide carboxylique ont été liés de manière covalente à Si3N4 à travers des monocouches autoassemblées (SAMs) du silane-amine (3-aminopropyl) triéthoxysilane (APTES). Enfin les anticorps anti-ochratoxine A ont été immobilisés sur les MLPs par liaison amide. Mesures électrochimiques ont été effectuées en utilisant une analyse Mott-Schottky pour la détection de l'ochratoxine A (OTA). L'utilisation de l'application de dosage compétitif grà¢ce à l'immobilisation des quantités fixe d'antigène (SA2BSA) et d'anticorps (Ab 155) a été mesurée respectivement contre différentes concentrations de sulfamides pyridine (SPY), avec et sans utilisation de MLPs avec une fonctionnalité de groupe carboxylique. La sensibilité de Biocapteur a augmenté quand MLPs ont été utilisés / Objective of this work is to overcome all those tedious and time consuming processes likefiltration and centrifugation which are used in in-vitro applications. Moreover, suchparticles which are suitable for use in lab-on-a-chip and biosensors systems are produced.Submicron magnetic latex particles (MLPs) with desired core-shell morphology wereprepared. Oil in water (o/w) magnetic emulsion (home-made) was used as seed of radicalemulsion polymerization of Styrene (St.) as a monomer and cross-linker divenylbenzene (DVB ) in the presence of potassium persulfate (KPS) and 4, 4'-azobis cyanopentanoic acid(ACPA) as an initiators. Particles surface was functionalized with sulfate and carboxylicgroups by using the initiators.A novel capacitance electrochemical biosensor based on silicon nitride substrate (Si3N4)combined with MLPs was developed. MLPs with terminated carboxylic acid werecovalently bonded to Si3N4 through a Self-Assembled Monolayers (SAMs) of the silaneamine(3- Aminopropyl) triethoxysilane (APTES). Finally anti-ochratoxin A antibodieswere immobilized on MLPs by amide bonding. Electrochemical measurements werecarried out using Mott-Schottky analysis for ochratoxin A (OTA) detection.Using application of competitive assay through immobilized fixed concentration of antigen (SA2BSA)and antibody (Ab 155) respectively was measured against different concentrations of sulfa pyridine(SPY), with and without use of MLPs with carboxylic group functionality. Biosensor sensitivityincreased, when MLPs were used

No / Microcarrier cell culture systems provide an attractive alternative to the conventional monolayer cell culture for cell amplification, due to their high surface area-to-volume ratio. Unlike enzymatic methods for removing cells from microcarriers after cell culture, which can lead to irreversible damage of the cells, microcarriers which release cells by temperature adjustment have been developed. This was achieved by grafting a temperature-responsive polymer, poly(N-isopropylacrylamide) (PNIPAAm), on the microcarrier surface. This review comprehensively presents various methods to prepare such thermo-responsive microcarriers based on PNIPAAm. These methods include the grafting-to technique, grafting-from technique, grafting-through technique, along with methods leading to PNIPAAm hydrogel beads, seeded polymerization, and non-covalent adsorption. The methods for controlling PNIPAAm grafting density, molecular weight and molecular architecture are also outlined. Further, the efficiency of cell attachment, proliferation and thermally-induced detachment of such thermo-responsive microcarriers is introduced and compared. (C) 2015 Elsevier Ltd. All rights reserved. / EPSRC