596,985 research outputs found
Ferrocene and Ferrocenium Modified Clays and Their Styrene and EVA Composites
In this work, ferrocene- and ferrocenium-containing salts were employed to modify montmorillonite. X-ray measurements show an increase in the interlayer spacing upon clay modification, which means that the larger and more organophilic cations were inserted into the gallery space of montmorillonite. Attempts to prepare nanocomposites of polystyrene and ethylene vinyl acetate copolymers lead to immiscible systems; the morphology of these systems was elucidated with TEM, XRD and cone calorimetry. The thermal stability of the composites is greater than that of the virgin polymer
On the Heegaard Floer homology of Dehn surgery and unknotting number
n this thesis we generalise three theorems from the literature on Heegaard Floer
homology and Dehn surgery: one by Ozsv Ģath and Szab Ģo on deficiency symmetries in
half-integral
L
-space surgeries, and two by Greene which use Donaldsonās diagonali-
sation theorem as an obstruction to integral and half-integral
L
-space surgeries. Our
generalisation is two-fold: first, we eliminate the
L
-space conditions, opening these
techniques up for use with much more general 3-manifolds, and second, we unify the
integral and half-integral surgery results into a broader theorem applicable to non-
zero rational surgeries in
S
3
which bound sharp, simply connected, negative-definite
smooth 4-manifolds. Such 3-manifolds are quite common and include, for example, a
huge number of Seifert fibred spaces.
Over the course of the first three chapters, we begin by introducing background
material on knots in 3-manifolds, the intersection form of a simply connected 4-
manifold, Spin- and Spin
c
-structures on 3- and 4-manifolds, and Heegaard Floer ho-
mology (including knot Floer homology). While none of the results in these chapters
are original, all of them are necessary to make sense of what follows. In Chapter 4,
we introduce and prove our main theorems, using arguments that are predominantly
algebraic or combinatorial in nature. We then apply these new theorems to the study
of unknotting number in Chapter 5, making considerable headway into the extremely
difficult problem of classifying the 3-strand pretzel knots with unknotting number
one. Finally, in Chapter 6, we present further applications of the main theorems,
ranging from a plan of attack on the famous Seifert fibred space realisation problem
to more biologically motivated problems concerning rational tangle replacement. An
appendix on the implications of our theorems for DNA topology is provided at the
end.Open Acces
Effect of a direct-fed microbial (Eubios 1090) in the presence of antibiotics (Carbadox or CTC-Denagard) on post-weaning pig growth performance and immune response
A study was conducted to determine the effects of a probiotic (Eubios 1090), in the presence of two different antibiotics, on performance in nursery pigs. A total of 216 pigs were weaned at an average of 21 d, blocked by initial body weight (BW = 6.79 kg), and distributed into 32 pens of 6 to 7 pigs per pen in an offsite nursery facility. Pens were randomly assigned to 1 of 4 dietary treatments (8 pens per treatment) that were fed throughout post-weaning phase 1 (day (D) 0 to 10), phase 2 (D 10 to 20), and phase 3 (D 20 to 34). Dietary treatments were: 1) Carbadox without Eubios 1090; 2) Chlortetracycline + Tiamulin (CTC-Denagard) without Eubios 1090; 3) Carbadox + Eubios 1090; and 4) CTC-Denagard + Eubios 1090. There was no interaction observed between the two antibiotics and addition of the probiotic. There was a tendency for greater gain to feed ratio (G:F) in phase 2 when nursery pigs received Carbadox compared to CTC-Denagard (P = 0.08), and a tendency for greater average daily feed intake (ADFI) in the overall nursery period when pigs were fed CTCDenagard compared to Carbadox (P = 0.10). Pigs that received the non-Eubios 1090 diets had greater average daily gain (ADG), G:F, and body weight (BW) during phase 2 compared to pigs that received diets containing Eubios 1090 (P = 0.05). In phase 3, pigs receiving the Eubios 1090 diet had increased ADG and G:F (P = 0.05). Between the Carbadox diet and the CTC-Denagard diet, the diet containing CTC-Denagard increased ADFI throughout the 3 phases. In summary, probiotic supplementation demonstrated negative effects in phase 2 and positive effects to growth performance in nursery pigs during the latter part of early post-weaning (phase 3)
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